Having played online poker for nearly a year I've had a chance to compare the two largest online poker sites. Both poker sites offer plenty of options for MTT (multi-table tournament) poker players. I like both sites. There are a couple of small advantages that I see with Full Tilt:
1. Hand Replayer - The software on Full Tilt for replaying past hands is far superior on Full Tilt. It is MUCH faster than PokerStars. For some reason on PokerStars you must click through each card being treated then antes, etc. It is very cumbersome and takes up valuable time when trying to analyze a poker hand and take notes on your opponents.
2. $ 2- $ 3 Tournaments: Sometimes you just feel like playing a small field (75-300 players) $ 2- $ 3 MTT to get some practice or build your bankroll while minimizing your risk. These are easy to find on Full Tilt but are nonexistent on PokerStars. I guess you can just always play a SNG tournament of a similar size on PokerStars so this is not really a critical issue.
3. Sizing Tables: On Full Tilt Poker I am able to make a table take up my own monitor if I desire. This is great if you are not multi-tabling. I know it is hard to believe, but not everyone multi-tables all the time. On PokerStars the tables have a fixed width and are not able to fill up my entire widescreen computer monitor.
The last two items are not probably major issues for most online poker players, but I really do think that the better software for replaying previous hands can be a major issue for some. I use both sites and will continue to do so. Full Tilt and PokerStars are respected in the online poker industry as evidenced by the huge numbers of players playing on each site. Elite poker professionals have associated themselves with each site to lend even further credibility. Both sites offer a full array of game selection and all the various forms of poker are available at every imaginable buy-in level.
For those players not ready to take the plunge into playing poker for real money, there are free games available on both platforms. It is a good idea to play for free if you are new to poker. In no-limit hold'em it is easy to lose a lot of money quickly through either an inexperience of a run of bad luck. Have fun but be careful if you decide to join the online poker craze.