Comedy:
Tim and Eric Awesome Show, Great Job!: I'm not saying that this is necessarily the best or funniest show of all time (though it's close for me), but I think it's probably more influential to modern internet humor than anything else. But maybe that's just me speaking out of my ass.
Check It Out! With Dr. Steve Brule: This is even better though. Absolute perfection. I can't explain how many times I've watched these and they still make me lose it every time.
Brass Eye: I don't watch a lot of explicit satire, but this probably the best satire ever made in the television medium.
Jam: This is even better as far as Chris Morris goes, though. Not as laugh-out-loud funny, but the mood is so unique.
Garth Marenghi's Darkplace: The silliest show I've ever watched. You have to love it.
Xavier: Renegade Angel: You can watch these so many times and discover something new to laugh at every time. Infinitely clever and stupid all at once.
The Eric Andre Show: Haven't watched season four yet, but the first three have all been quite consistent.
Seinfeld: Me and my mom can quote this entire series to each other. I pretty much can't stand any show with a laugh track but this is the major exception.
Home Movies: Cute without being sickeningly twee. Though sometimes the more overly clever dialogues are a bit annoying. I still love it though.
Drama, Sci-fi, etc.:
The Twilight Zone: Some episodes are corny but overall there's no denying these. Timeless to this day. It's a Good Life is one of the scariest things I've ever seen which is why it's still my favorite episode. I especially love the more sci-fi-oriented ones.
The X-Files: It's not without some lame episodes, but if you like this stuff you'll learn to find something in all of them. I'm a sucker for this kind of stuff anyway.
Twin Peaks: I used to be a HUGE Lynch fan and I still like him a lot. This and the connected movie are probably his best achievements.
Stuff I watched as a kid:
SpongeBob SquarePants: Not going to buck this trend from the thread. Out of all of these this is what I'd choose to watch any day.
Courage the Cowardly Dog: I think this made me more interested in surrealism and the bizarre than anything else.
Hey Arnold!: Phoebe was my first waifu I think, still pretty much what my type looks like.
Angela Anaconda: I watched this outside of the Digimon movie!
Kenan & Kel: GHOST STORIES??? I THOUGHT YOU SAID TOAST STORIES!
I don't really watch anything that's actively airing except Adventure Time which I've watched since it started and can't give up on now since it's nearing completion (which I'll be relieved by, it's stretched a bit thin and inconsistent). I can't be bothered to keep up with release schedules; I don't watch anime until it's finished airing for the same reason. J-drama probably counts as weeb shit so I won't mention that. I haven't seen a ton of it anyway.