Have used Kraken (One of the few real possibilities for fiat exchange if you want €), Bittrex (because of the many coins they offer) and Bitfenix (to get some IOTA).
Personally I like all three of them but without Kraken I wouldn't have a real shot at trading back to fiat without having to pay ridiculous sums.
Makes sense. Perhaps I should use Kraken in case I want to withdrawal?
If you want Euro as a fiat currently I highly suggest to at least get the verification process there started. Takes some time but it just feels safe to be able to just sell if I should ever feel the need to without having to pay any overpriced fees.