Full Tilt
or
Poker Stars
I started playing on pkr.com
I just cant get used to pokerstars/fulltilt... its so boring to play poker there, once you are used to a real 3d poker 
they're both good. play both
depending on many other factors as well but stars favors players who play higher volume and higher limits. you can make a nice living just making supernova and supernova elite even if you're a break even player. I prefer tilt's software over stars and it is "said" that there are more coolers on stars and more bad beats on tilt. I personally do not think that is true since I don't buy into the rigged conspiracy theorists n such lol but whatever..if you play less volume and limits then tilt's rakeback deal u can get with rakeback pros is better. I also prefer full tilts choice of tournaments and such but more SNG's seem to run on stars like the 18 mans and 27 mans and such. Clearly, it is based on many other factors but if I were you, I would just play both and play what your good at and what is running.
I just cant get used to pokerstars/fulltilt... its so boring to play poker there, once you are used to a real 3d poker
Yeh I'm liking PKR at the mo.
I would play on both, but if I had to choose I would go with FTP right now. I'm addicted to rush poker.
Sigh. More generic questions :P
We need more information. What games do you play? Cash games? Single table SNGs? Guarantee tournaments?
What's more important to you in a poker site - the amount that you win? The quality/security of the software? Something else?
You need to put your question into context before we can answer it effectively. What you're asking at the moment is akin to asking "Who is the better sportsman? Usain Bolt or Roger Federer?" without giving us a category on which to base our decision.