This was probably done before, but I don’t remember anything recent. What are your favorite or what shows do you think had/have the best theme songs? In no particular order, I would say:
Psych
Gilmore Girls
Hawaii 5 0
Hawaii 5 0 is a great one.
For whimsy, I always liked the theme to It’s Garry Shandling’s Show.
(In before the forum move.)
I also love the Psych theme (the full version, of course, not the shortened one.)
A couple of months ago this same subject came up on a different forum. Skim through the comments here for lots of suggestions (including many Youtube links.)
I like the second theme from Monk, “It’s a Jungle Out There” by Randy Newman.
I’ve never watched an episode, but my favorite theme is the Peter Gunn theme by Henry Mancini.
And I’ve always liked the Doctor Who theme.
Do you mean theme songs? Or title music (lacking words)?
As for songs, I doubt anyone’s theme song beats that of The Addams Family.
As for title music, MASH* is up there (it’s borderline, because it WAS a song, but was instrumental for the TV show). At the time, the Miami Vice theme was quite popular. The intro music to Star Trek: The Next Generation was quite good.
God there’s so many. How do you pick?
I don’t this one has ever come up in these threads before:
The song came at the end of each show, instead of the beginning. Michael Parks, the star of the show, was the singer. It was a minor pop success, hitting #20 on the Billboard charts. The show lasted only one season.
Me and my aunt were not big S.W.A.T fans but we tuned in once a week to listen to the theme song.
And even before then, as a besotted 10 year old Baretta could do no wrong. Especially in his theme song.
I like the theme song from* Shameless* (U.S. version) and the one from Boardwalk Empire. I looked up the one from Shameless on YouTube and was surprised the singer was a guy.
There are hundreds I could list. Here are some off the top of my head.
Terriers
The Incredible Hulk
The Littlest Hobo
Jamie and the Magic Torch
Grange Hill
The Borrowers
Everyone knows the words to **‘The Golden Girls’ **theme, it would be pointless to link to it.
Very fond of the opening to The Prisoner. The music is spiffing. Of course, it’s the catechism that really stands out… “Where am I?”
2nd Jonny Quest.
The Jetsons and The Simpsons – strangely similar – are goodies.
St Elsewhere
For some fresher entries, I’ll suggest…
Attack on Titan
Game of Thrones
And the other way around, of course. 
Lots of good ones mentioned already. A few of my favorites are:
FLCL closing credits - Ride on Shooting Star
Cowboy Bebop opening credits - Tank! (Yeah, that’s the long version. The show just had an edit of that.)
Squidbillies Theme Song don’t like country? There’s literally dozens of different versions, in totally different styles. Yes, even Shatner did a version of the alternate lyrics.
Gilligan’s Island is the archetype for explanatory theme songs. Gary Shandling Show completely deconstructed the form.
ETA: Sorry, I have disrespected the true archetype, The Beverly Hillbillies.
Greatest American Hero
Justified
My favorite “Deep cut” theme song that few others remember is the theme to the 90s Syndicated series the Untouchables. I haven’t seen the show in two decades but I still hum the theme sometimes.
I’m also a big fan of the theme of the show Alien Nation but that one is probably better known.
Another one I enjoy is My So Called Life.