I used to be a ESPN.com guy, but have pretty much boycotted the site (still read Simmons, Stark, free Gammons) due to their annoying and in your face ads and everything being insider premium content.
Foxsports.com, Im not a big fan of their website layout or writers.
CBSSportsline is pretty good. Almost all of my fantasy sports leagues are on CBS, so Im on there alot of times by default.
But I now find myself going to Yahoo Sports for all my national sports news, box score scavenging, and player info. Great writers, excellent layout, the ads are presented in a non annoying way (no pop ups or force minimize ads).