PS is interersting with their Ligue, a good idea which should be implemented by other rooms. 888 has a lot of Super Turbo tournaments as well as additional modes like BLAST or FLOPOMANIA. However, in my firm belief, you should try ACR or RedKings as well if you do not want to fight your way through 8K players in freerols. In common, one room differs from another by the numbers and types of tournaments. But if you a cash-tables fan, then it doesn't matter which room you chose. All you need is a full short/long table and appropriate bankroll.
Since I started playing on PokerStars, is the only room that game, Pokerstars has the best software and is quick payments, and has good freerolls, other than the mobile application is very good and easy:heeeellll
I play PokerStars and sometimes 888 Poker freerolls,
I play PokerStars more because I participate in leagues and many different promotions and draws of prizes and good tournaments, every poker room has + and -, for me PokerStars is an excellent poker room!