I'm a big fan of Yahoo b/c it's free and I don't see the other sites being any better than Yahoo.
Also, if you create a league, you can set roster and scoring options to whatever you want, along w/ playoffs, everything. You can set the point values as well. Although I'd rather you have a couple options for league types when joining a public league, I love the custom leagues. I'm the commish of two, and I have an openings in one if people are interested.
League ID: 99257
10 team, h2h, w/ some good scoring options that differ from standard Yahoo.