The Office. Nothing else is even close. On my sixth or seventh time thru currently.

Star Trek TNG. I have seen it more than I can count. Fave show of all time. I do skip a small number of episodes. Shades of Gray (clips episode, common 80s TV show trope) Sub Rosa (Ghosts in a show that constantly says they don't exist) Masks (lol computer virus turns the ship into Mayan temple) Code of Honor (feels like a leftover script from the canceled Star Trek Phase II show and prob is like much of season 1) Frame of Mind (it's well done but I hated it for whatever reason)

Fave episodes are. Relics. Yesterdays Enterprise. Genesis

Futurama, Seinfeld, King of the Hill, and Arrested Development

Star Trek. I've rewatched them all on Netflix and they're always on on Space Channel. I don't think a day goes by without watching some Star Trek. (Exception for Discovery, don't like it) I've also recently watched the Expanse first 3 seasons again.

Star Trek Guilt and Regrets (Picard) is mostly good for fan service with the old cast. The story on its own is kinda meh. Star trek works best when dealing with one thing per at most double episode with some background story lines. Longer stories just seem to drag on. It also sort of forces you to watch them in order while I prefer to (re)watch random episodes. When Picard was airing on Space Channel they put a TNG episodes featuring Picard right after, that was actually more enjoyable than the new show tbh. It is very well made, but despite it all looking very grand, it feels very small for some reason.

I have rewatched all of Family Guy at least 5 times, some seasons more. It's basically what I turn on whenever I'm eating. South Park and Futurama are the same with slightly fewer rewatches.

I've probably seen every episode of Friends at least six or seven times, but I've only ever watched it through in order once.

From front to back, it's 24, which I've done three times.

I'll start of with a few then add later then I think about it. Won't count anime or cartoons here

Stargate ALL
MacGyver (original)
Star Trek ALL
Angel
Sopranos
A-Team
MASH
Airwolf (first three)
Knight Rider
Love They Neighbour
Mind Your Language
X-Files
80s british comedies (usually short series so easy to rewatch)

I watch through Burn Notice and Avatar the Last Airbender at least once a year. Besides those two I don't really rewatch series all that often. The closest would be Stranger Things which I've watched through at least four times by now.

Buffy the Vampire Slayer, most probably. Though I watched tons of Dr. Quincy and Murder,she wrote with my mom as a kid and a teen. Arrow is slowly catching up.

Saint Seiya/Dragonball/DBZ/Ulysses 31/Jaice and the Wheeled Warriors/Captain Tsubasa (hell, pretty much anything that ran on Club Dorothée and the like) for Anime