As I see you are from germany.
You are limited on the pokersites on the Whitelist from GGL (Glückspielbehörde der Länder).
These are GGPoker, pokerstars, 888Poker, partypoker, BWIN, and BPremium, last 3 are Partypoker Skins.
Playing on any other poker site is illegal for germany resident poker players and can give you up to 6 months jail.
I think there are two options that are most relevant at the moment. These are 888 and GGPoker.
Both of these sites are quite safe, have good, interesting promotions and a wide range of different types of poker. I think both of these options are worth considering, or even better, creating an account on each of them and choosing what is most interesting for you.