'Man City among the greatest sides I have seen - but who are yours?'

In my time working as BBC Sport's chief football writer, I have been lucky enough to see some of the game's greatest teams.

But watching Manchester City complete the Treble in Istanbul made me think about some of the best sides I have covered.

City's feat in becoming only the second English men's team to win the perfect Treble of the Champions League, Premier League and FA Cup is confirmation they must be ranked among the greats.

Erling Haaland's goals and power provided a significant point of difference but there was brilliance in every position delivered by the likes of Kevin de Bruyne, Ilkay Gundogan, Jack Grealish and many more.

The first 45 minutes of their 4-0 win against Real Madrid in the Champions League semi-final second leg was one of the most exhilarating exhibitions I have ever seen.

There will be the inevitable questions about the Premier League charging City with 115 breaches of financial regulations - allegations the club fiercely deny and will fight strenuously - but, judged in the football context, they are a quite magnificent football team.

So who are the other greatest men's sides I have seen in my career? This proved too hard to whittle down into one article, so I have only covered the years I have worked for the BBC.

See what you think of my picks and let me know who the greatest side is that you have had the pleasure of watching by using the form at the bottom of this page.

Klopp's rejuvenated Liverpool

Jurgen Klopp's transformation of Liverpool after succeeding Brendan Rodgers in October 2015 took its time to hit full stride, but when it did they provided some of the most exciting attacking football seen anywhere.

Sadio Mane and Mohamed Salah formed a deadly triumvirate with Roberto Firmino, but it was the sale of star man Philippe Coutinho to Barcelona for £142m in January 2018 that enabled Liverpool to hit a spectacular next level.

The money was initially spent, £75m of it, on Southampton defender Virgil van Dijk as Liverpool reached the Champions League final at the end of that season, losing 3-1 to Real Madrid.

Klopp spent the rest of the Coutinho cash on Roma's brilliant goalkeeper Alisson Becker, Liverpool going one better the following season, beating Tottenham in the Champions League final in a run that will be forever remembered for the second-leg semi-final at Anfield when Liverpool beat Barcelona to overturn a three-goal deficit.

Next up was a first league title in 30 years, there was also the chase for an historic quadruple in 2021-22 - in which they missed out on the Premier League title to Manchester City by one point - and there was another Champions League final loss to Real Madrid, but the FA Cup and League Cup were won.

Quite simply, one of the outstanding teams of the modern era.

The Real of Bale, Ramos, Ronaldo and many more

Real Madrid will always feature in any list of great teams but, as this is shaped by those watched in person, one era stands out above all others, starting in 2014.

I have been there for five of Real's Champions League wins, stretching back to Zinedine Zidane's left-foot volley, a moment of the purest sporting beauty, that won the 2002 final against Bayer Leverkusen at Hampden Park.

More riches came in quick succession later on in a team dominated by the force of personality of Cristiano Ronaldo and Sergio Ramos but also blessed with the enduring brilliance of Luka Modric, Toni Kroos and Karim Benzema and - before it sadly turned sour - the glorious talent of Gareth Bale.

I was in Lisbon in May 2014 to see Ramos's headed stoppage-time equaliser set up an eventual 4-1 win against arch rivals Atletico, then in Cardiff three years later when Juventus were beaten by the same scoreline.

Bale's final came in Kiev in 2018 when Liverpool were beaten and there was another to see in Paris in 2022 when Vinicius Jr's winner sunk Jurgen Klopp's team once more.

This was a world-class team able to win in different ways, its enduring nature confirmed by Benzema and Modric receiving five Champions League winners' medals while Kroos, Ramos and Ronaldo won four while at the Bernabeu.

Guardiola's Barcelona and beyond

Pep Guardiola's opening season in charge of Barcelona brought his first Treble - crowned by a magnificent 2009 Champions League final victory against Manchester United in Rome's Stadio Olimpico to add to La Liga and the Copa del Rey.

United actually threatened to over-run Barcelona in the opening moments but once Samuel Eto'o opened the scoring this was a peerless, one-sided demonstration of what Sir Alex Ferguson's labelled the Catalans' passing "carousel".

Lionel Messi emphasised his greatness with a brilliant second-half header, a United side boasting players such as Cristiano Ronaldo - playing his final game before moving to Real Madrid - and Wayne Rooney utterly outclassed.

This was the Barca of Xavi and Andres Iniesta in midfield, with Sergio Busquets the bulwark. Above all, it was the Barca of Messi.

If anything, their 3-1 win over United at Wembley two years later, with the great David Villa in the ranks and on target, was even more emphatic, the waves of pressure applied with a brutal brilliance that overwhelmed Ferguson's team. It was not quite perfection but it was not far off.

Barcelona had acquired two more geniuses in Neymar and Luis Suarez when they won another Champions League with a 3-1 win over Juventus in Berlin in 2015.

I was privileged to watch all three victories by a truly great side and it was Guardiola who moulded them, Messi who inspired them.

Spain rule the world

The label of perennial under-achievers hung heavily on the shoulders of a hugely gifted Spain side until Fernando Torres' winner gave them their first major crown for 44 years with victory over Germany in the Euro 2008 final.

It was the start of an era of world domination based on an amalgam of Barcelona and Real Madrid, who put old rivalries aside for the greater good, firstly under Luis Aragones then Vicente del Bosque.

Spain had defenders of the calibre of Carles Puyol, Gerard Pique and Sergio Ramos. Midfield quality came from Xavi, Andres Iniesta, Sergio Busquets, Cesc Fabregas, Xabi Alonso and David Silva, while Torres and David Villa provided quicksilver brilliance in attack. Iker Casillas was a world-class keeper.

The World Cup followed in 2010, a desperate final against the Netherland in Johannesburg which contained 14 yellow cards and a red for Dutch defender John Heitinga, settle by Iniesta's extra-time winner.

If these were attritional victories, the full range of Spain's talents flourished in a devastating 4-0 thrashing of Italy in the Euro 2012 final in Kiev, three successive major tournament wins in a truly golden period sealed in style for them and for all of us who witnessed it in person.

Manchester United - take your pick

Manchester United's great teams can be plucked from many eras and, as this is based on first-hand reporting experience, the Treble-winning 1999 team comes a year too soon - but how can we ignore that stellar season?

The first English team to win the Champions League, achieved so late and so dramatically against Bayern Munich in the Nou Camp, the Premier League and the FA Cup in the same season.

And look at how they got there. Inter Milan were beaten in the last eight, while a high-quality Juventus side were overcome in the semi-final, United winning 3-2 in Turin despite going 2-0 down.

This is the very definition of a great team, but for this particularly criteria I take a leap forward to the team that won Sir Alex Ferguson's second Champions League on penalties against Chelsea in Moscow in 2008.

United's attack contained Cristiano Ronaldo, Wayne Rooney and Carlos Tevez, while central defence was patrolled by the world-class duo of Rio Ferdinand and Nemanja Vidic. Paul Scholes was in midfield alongside Michael Carrick and Owen Hargreaves, while Ryan Giggs was still very much a force. Edwin van der Sar was an outstanding keeper and vital in the penalty shootout.

This incarnation of Ferguson's United also won the Premier League, the second of three successive titles - a feat not repeated until Manchester City won their third in a row in 2022-23.

Mourinho's Chelsea glory boys

Roman Abramovich's riches had already started to transform Chelsea for one season under Claudio Ranieri but defeat by Monaco in the Champions League semi-final convinced him he needed something special - or should I say "The Special One"?

Jose Mourinho made one of the most spectacular and memorable managerial entrances in the story of English football and was able to back it up by delivering Chelsea's first title in 55 years.

Mourinho, who came to Stamford Bridge after winning the Champions League with Porto, had foundations in the shape of captain John Terry and future all-time great Frank Lampard, but added the talisman Didier Drogba, alongside with his Porto defensive stalwarts Ricardo Carvalho and Paulo Ferreira. Arjen Robben also arrived.

Mourinho shaped a Chelsea team that served the club superbly for years to come, bolting fierce defensive discipline and streetfighter qualities on to serious attacking threat with Lampard both an outstanding midfield force and a world-class source of goals.

Mourinho made it two titles out of two in 2005-06, although he saw his Champions League aspirations thwarted by Liverpool in a pair of semi-finals.

Yes, it ended as it do often does with Mourinho - sourly. But this was a great manager at his best and this was the start of Chelsea's golden years.

Wenger's 'Invincibles'

Arsene Wenger was a transformative figure following his appointment as Arsenal manager in 1996.

He adopted a cerebral approach, moulding a group of outstanding talents into a purists' dream, mixing style with steel to superb effect.

Wenger brought the young Patrick Vieira to English football, where he was joined later in his reign by fellow Frenchmen Emmanuel Petit, Thierry Henry and Robert Pires. Dennis Bergkamp was signed by predecessor Bruce Rioch but flourished even further under Wenger, while fellow Dutch superstar Marc Overmars joined him.

Wenger wisely kept the fiercely competitive bedrock of keeper David Seaman, captain Tony Adams, Steve Bould, Lee Dixon and Nigel Winterburn then slowly changed, the guard - Tottenham captain Sol Campbell switching sides in north London in a seismic free transfer move in July 2001.

Among many shrewd buys, Wenger also signed the teenage Nicolas Anelka, who helped Arsenal win the Premier League and FA Cup double in 1998, which was also won again four years later.

The crowning glory among many glories?

This has to be 'The Invincibles' who went the entire top-flight season unbeaten in 2003-04 - the first to achieve this remarkable feat since Preston in 1888-89.

Arsenal's team on the day they wrote history by beating Leicester City at Highbury on 15 May 2004 was: Lehmann, Lauren, Toure, Campbell, Cole, Ljungberg (Keown 87,) Silva, Vieira, Pires (Edu 70), Bergkamp (Reyes 82), Henry.

Now it's your turn. Use the form below to tell us about the greatest side you have seen and a selection will be published on the BBC Sport website and app.

If the form doesn't load properly, go straight to it here.