In Europe, I always say that Barcelona and Real Madrid are the ones to look out for.
I had three very successful years in Germany with Borussia Dortmund, but I had the opportunity to move to one of the biggest clubs in the highest-profile league in the world.
You can never know if there will be a second Cruyff, someone with a great personality who can grow up and make it into the squad of the club they love. But what is certain is that, in the Champions League, there will be big clubs producing these players forever.
Every coach wants to train Manchester United; it's one of the biggest clubs in the world.
Liverpool are a massive club with a big history that has won many trophies over the years, and as soon as I was told of the possibility to come here, and I knew the manager wanted me, I said yes.
That is the issue with signing young players from other big European football nations - at some point, they will want to go home.
Pressure, responsibility - I'm used to playing in big clubs.
I've been in big clubs, but I want to achieve titles with Valencia.
In Germany there are only two dominating teams, Bayern and Dortmund. In England the top group is broader.
United are one of the biggest clubs in the country. They're a massive team; they want to win the title. They spent a lot of money, like a lot of the big teams.
Bayern Munich is as big a club as Real Madrid, if not even bigger.
With the big clubs embracing women's football and the professionalism you see at the likes of Liverpool, Birmingham, Arsenal and my club Chelsea, it's really impressive. We're making great strides.
Having coached Ajax, Barcelona, the Netherlands, FC Bayern, and Manchester United like I did, it is difficult for any offer to be interesting.
I know the questions will be around the money, the amount Chelsea had to spend to bring him here but that's the reality of modern football. Big teams only want big players, big players are in big clubs, big clubs want to keep their big players.
Every player thinks he's Maradona when he joins a big club. That happens to all of us, but then you start to notice it in the younger players. You see kids who think they're rock stars, wearing extravagant clothes and driving fancy cars... and sometimes you have to take them aside and have a word.
City's boss and owner came with a very good proposal. They showed me that City has the ambition to be one of the biggest clubs in the world. This made it easy to make the move. Money was never important.
I started at Benfica: not as big but one of the biggest clubs in Portugal. I've played for Real Madrid. Then I moved to Manchester United, from a giant to another giant.
I know what it means to play for a big club. Big clubs, it's like that: if you win, everything is good. If you lose, it's your fault, especially defenders and goalkeepers.
The Premier League is just a really cool league, the most interesting in the world, but you must always respect other big clubs and leagues.
For me, Real Madrid are just like any other club, like Barcelona, Milan, Bayern Munich, or Inter. Just another big club.
I have been fortunate enough to play in some big clubs all over the world and in some important games and win trophies.
Without being disrespectful to Leverkusen, playing for Liverpool helps me more because I am playing for one of the biggest clubs in the world, and I have no regrets making this step.
There are lots of big clubs, and having played for Arsenal, they are also one of them. It's a huge club, and I was there.
Why PSG? Because to leave United, the biggest team in England, you need something like PSG, which is the biggest in France. I could not play in another English club.
Where would I go from Liverpool? It is one of the biggest clubs in the world and I am too happy here to move.
