one i recommend NOT to watch is Weeds. was good first 3 or so seasons, then went downhill from there and season 7 started this past week and it's fucking terrible. didnt think it could be worse than season 6 but it's looking to top it, after just 1 episode.
Always Sunny in Philadelphia
South Park
Family Guy
Entourage
All great 30 minute shows. the writing in Always Sunny is brilliant, show is probably the funniest show I've ever seen.
EDIT:
would also add Forensic Files and Hardcore Pawn, and Operation Repo is so stupid but I always find myself watching it.
TruTV owns.