I subscribe to FBGs as a staple and select one other each year on a trial basis. Last year it was KFFL and this year FantasyGuru, two years ago the Huddle. None of these seem to reach the IDP depth I'm looking for and they are far behind FBGs.
I also tap into FFFtoday for their idp write up, which I find useful.
KFFL's Hot Off The Wire player news seems to be a little more detailed than competitors and I use its player watch list to send me updates on selected players.
FantasyGuru provides a tiered cheatsheet that I like and the site seems to be improving.
I've moved on from The Huddle, which is a decent, cheap site for simple redraft leagues.
While the content at FBG is overall far superior, there are two other things that set FBGs apart
1) the message boards are an extremely useful place for exchanging ideas, asking questions, getting feedback.
2) the offseason daily emails and training camp reports are way cool and unique.
I ignore almost completely Fox, ESPN, Yahoo, CBSsportsline.