Well, I've done some tinkering and asking around...
What I've heard from ESPN: Wonky as hell. Down a lot of the time. This comes from a few different sources and all have said they absolutely loathe the site.
CBS Sportsline: Much more steady, less downtime. Easier interface, good player information and news. You don't have to go picking around a lot of different sites for news if you don't want to.
So. I will create fake leagues in each and see how I like it. Does anyone really have a die hard preference for ESPN because from what I've read and asked from friends who do Fantasy Football religiously, CBS Sportsline seems like a better choice.
Edit: Evidently, you need 10 players for CBS... so... unless we get 2 more who want to join, I guess we'll have to go for ESPN. Crappity.