Hands down, the gaming experience is better on the PC. The graphics are better, the map packs are free (unlike XBOX/PS3), and you don't have anywhere near the issues as you do on XBox Live or PSN.
Furthermore, the precision in which you can control your player is much better than you'll find on any of the consoles.
I've said many times that it would be cool if gamers could compete across the platform such as XBox vs PC vs PSN but it would grow old for the console gamers because they would be slaughtered when going up against PC gamers.
Honestly, if you are looking for playing a lengthy campaign mode, not happening in these games. The multiplayer is the big selling point.