Firefly was mind-blowing, back in the day. So was Stargate SG-1. CSI, for all its faults, was fascinating at the time. Blue Planet was gorgeous. Fullmetal Alchemist. Pushing Daisies. Dead Like Me. The Middleman. Wonderfalls. Numb3rs. The Last Detective. Have Gun Will Travel.
I have a soft spot for Dr. Who, and the old Star Trek stuff. Loved House. For all it's flaws, Sherlock was excellent. Dexter was fantastic for a little while. The X Files - so much wrong with it and honestly hard to care because of the acting. One Punch Man. The Expanse. Poirot. MASH. Miss Fisher's Murder Mysteries. Wire in the Blood. Babylon 5. Titus.
I liked Hogans Heroes. Highlander: the Series. Airwolf, when I was young and uncritical . Forever Knight.
There were some middling shows with exceptional episodes - Supernatural, "jump the shark", others that were good.
I haven't watched much tv lately. It's hard to like fiction as much as I used to.