Well, I found Berlin some decades ago quite impressive, culturally. Don't know how it is now, but via via I was told it's less relaxed. Prague for was then very nice, and not too touristic.

But, like Bruges ( and Gent) in Belgium, are so, I don't know, nice, relaxed and pittoreske 2b at.

Bruxxelles, London and Paris are just street & metrowise a mess. If you are OK with that though, and know the places to be, and you can find your way, your experience can be very special. What really helps in those big cities is to have the company of some locals (friends,). That would definitely amp up your experience in some of the "bigger" European cities, imo.