Can I suggest to provide some preferences according to size?
I mean, of course Paris and London are great! But how can you ever compare them to cities such as Zurich or Lisbon? As they are bigger, they intrinsically have an advantage over the others. So I suggest to compare different leagues
Let's say "champions league" is dedicated to the biggest cities: London, Paris, Moscow, Istanbul (may be Madrid, Athens, Rome and Berlin)
The second division might include the medium sized cities: Barcelona, Milan, Frankfurt, Amsterdam, Stockholm, Brussels, Prague, St-Petersburg, Budapest, Lisbon, Vienna,...)
A third division might even be introduced for the "smaller" cities...
Europe has got a bunch of great cities,but here are my favourites per division:
1st div) London (though I didn't see Istanbul yet, which might come close ànd has got a huge climatic advantage
2nd div) Lisbon, ooh I loved that city! And I must add Brussels in my favourites for obvious reasons