By “television musical” I mean the entire series, be it a one-shot, a mini series or the entire series, and definitely not a musical episode in an otherwise non-musical series or a showing of a movie previously shown of the big screen,
My Beloved’s favorite television musical is the Rodgers and Hammerstein’s 1965 musical, starring Lesley Ann Warren (which I know is a remake of the 1957 original television special starring Julie Andrews, but she hasn’t seen that one…yet). I will give mine in a bit, after a family trip to Trader Joe’s.
Presumably you’re talking about Cinderella. I’ve always really liked that version as well. In fact, I mentioned to my daughter a few times over the past year or two that I wouldn’t mind rewatching it and, in fact, my work youtube account keeps trying to get me to watch clips from it.
Most definitely…and sorry about that.
Crazy Ex-Girlfriend. Consistently good songs from start to finish and a story that is both funny and with much to say. It also nails the ending with one of the best for a TV series ever.
Seconding Crazy Ex-Girlfriend. I also thought Galavant was underrated.
Have to give a lot of credit to the late Adam Schlesinger who was the executive musical producer and co-writer of many of the songs.
Fan of that, too. Alan Menken wrote the songs.
Me, too. It was the first time I saw that a musical could be snarky and funny (as well as, admittedly, sappy). Leslie Ann Warren was supposed to be 100% sappy, but as we’ve seen from her subsequent roles over the years, she had a rather subversive strain.
The Prince (Stuart Damon) was sarcastic, and the Stepsisters (Barbara Ruick and especially Pat Carroll) were funny, and rather touchingly no competition for Cinderella.
It was gloriously un-wholesome.
If Girls5eva counts, that’s what I would vote for. I think every episode has a song of some kind, but it’s not restricted to characters breaking into song Broadway-style. (Wikipedia classifies it as a musical comedy, for what it’s worth.)
Hoping Ringo’s 1978 tv special counts. It was a prince and the pauper story, with Ringo encountering - and then switching roles with - someone who strongly resembled him and born at the same time, Ognir Rrats.
This one in particular is a pitch-perfect parody of a genre I like to call “every other song recorded by Nancy LaMott”:
I really enjoyed this show!
Galavant is also my favorite.
What? No love for Cop Rock? 
I actually quite liked MTV’s boy band parody, 2gether. Was first a TV movie, then a series.
I wanted to say Pushing Daisies, or The Drew Carey Show, but they don’t quite qualify. 
Hoping this qualifies - Mary Tyler Moore’s “Mary” variety show, which often had (too much?) singing, airing for exactly three episodes in '78 before getting the ole neck-cane. Some of the supporting cast had Dick Shawn, Swoosie Kurtz, and a young Micheal Keaton and David Letterman. I remember wading through its dross and finally coming across a fine musical number (which I hoped to post here from youtube but couldn’t find) about laboratory rats singing about the woeful situation they’re in, with the featuring moment having Letterman - fully dressed in a rodent suit - singing imploringly into the camera, making it the most soulful broken fourth wall ever.
This would be your favorite television musical?
Right - I forgot about my Ringo post earlier.
Wow. Can’t decide.
I personally liked singing along with Dr. Horrible.
If we’re talking streaming video, then the two-season run of Schmigadoon is absolutely the winner.
If we limit it to “traditional” TV then Galavant was the best I’ve ever seen.