I think it really depends on what you're looking for and here's a breakdown of what I've found:
Absolute poker has a large number of $50 freerolls, every two hours (sometimes every hour!). They also allow re-buys for 50 cents, which can get the pot to be much larger. On Several occasions I've seen the $50 freerolls get to well over $150. BUT, the drawback to Absolute is that they allow 5000 people to register.
VC poker is sometimes difficult to get into if you live in North America, the same with
Titan. They run only a few $50 and $100 freerolls a day. The players are much tighter on this site (as a general rule, you'll find donks everywhere though.)
Poker.com has an interesting setup, every 4 hours with 3 NL Holdem tourneys a day, with a HORSE freeroll and a Bugadi freeroll. If you accumulate player points you can become eligible for many larger freerolls as well (Daily $1000 freerolls, weekly 10,000 and monthly 50,000.)
I can't say much about FTP, but everyone else seems rather pleased!
Good luck and may all your hands be winners.