-Seinfeld
-Friends
-That 70's Show
As far as comedy series go, I might watch "Malcolm in the Middle" if there is absolutely nothing else to watch, but I don't really like it.
For all the other "serious" series, I really like "House", and it's the first 1 hour long cable tv series that I follow, ever. I just couldn't get into 24 and everything else is just dumb IMO.
As for the HBO/Showcase series, I used to watch "Dead Like Me", but it was cancelled after the second season


EDIT: Forgot about the cartoons

I really love "Family Guy", but I also watch "Futurama" and the new or very fresh episodes of "The Simpsons" on sundays, although they pretty much all suck now

EDIT2: Fuck it, simpler to make a list, that way we can quickly see what everyone likes. I watch:
Sitcoms (religiously):
-That 70's Show
-Seinfeld
-Friends
Comedy series:
-Malcolm in the Middle (occasionally)
Serious series (cable):
-House
HBO/Showcase:
-none for now, but used to watch Dead Like Me
Cartoons:
-Family Guy
-Futurama (occasionally)
-The Simpsons (only fresh/new episodes, occasionally)
-American Dad (seen the pilot episode and liked it, most likely will watch it)