[alain94040]

The successful ones are now Parrot and Criteo. Remember those? But there are plenty of small startups that are doing challenging stuff. Interested in machine learning? Check out mipsology.com

If you want to be paid well, you need to work for a company where the technology is the product. Writing Java for a bank? The software is not the product, so you won't be respected like in Silicon Valley.

[user5994461]

Depends what you mean by Bank. If you talk Investment Bank, Edge Funds and HFT you'll probably be fine ;)

But those are in NY/London, not Paris.