I can’t remember very well – I’ve only been once – but I’ve been told from someone who lives there that Brussels is a good city for pianists. Many small cafés and restaurants are still hiring cocktail pianists on a regular basis and the entire city’s population is very art-oriented.

Paris is no good – it’s a great city to study classical music, however. But I’ve been myself, and one of my university teachers lived there for a few years while studying at the conservatory back in the day and the music scene over there is quite sad apparently. Most bars and restaurants are more oriented towards electronic and industrial music without much interest to hire anyone. Plus, most Paris residents have an aversion for tourists (not dissing anyone here, but I’ve been there and felt it – everyone I spoke to who’s been there felt it too).

I can’t say about the other cities you mentioned though.

I suggest beginning with the 4 main musical hubs Germany, Japan, UK, and Mexico.

Thanks for your contributions guys, so you mean that studio work/live work (for other artists) is possible here in EU too?
Or did you mean playing live with your local band?

I lived in Italy for 17 years and toured quite a bit of the continent; based on that experience, there are a couple things you should realistically consider.
(1) unless you have a “secured” job, your visa is only valid for 90 days.
(2) gigs in any city are based on connections, and 90 days is quite an ambitious time-frame to get to know other musicians who will hire you and acquire a passable knowledge of the local language.

Honestly, your primary concern will need to be the legality of your presence in the country, each of which has its own laws about foreign workers. Location will be a secondary concern, as each of the major cities has a flourishing music scene.