TOS is definitely the cornerstone, but even there there's inconsistency. Single-continuum timeline, as in "Tomorrow is Yesterday"? Or multiverse, as in "Mirror, Mirror"? What about those instances in the third season when no one gave a crap any more and Gene was gone? "Day of the Dove" always makes me hurt because it places main engineering at the back of the saucer rather than in the secondary hull. And then there's TAS, which follows on in the tradition of earlier TOS for the most part, despite painful '70s animation production values (I'd love to see it remastered, with all of the old voice performances re-used -- albeit with all the characters voiced by Jimmy Doohan and Nichelle Nichols at least altered).
I'd like to see Gene's vision for TMP, not the movie that ended up being a war between him and Harold Livingston, and that didn't have finished VFX in time for the premiere. Some of that comes through in the novelization, that Gene wrote. Not going to get into a dissertation on the rest of the films here...
TNG is... fraught. The first season was clunky as hell for most of the first half. Toward the midpoint we got a couple episodes that had some good Trek peeking out around some pretty cringe dressing -- "Justice" and "The Battle". After a bit more faltering, I feel they hit their groove starting with "We'll Always Have Paris". Even with the writers' strike that shortened and heavily impacted season two, it's still my favorite. I'll watch straight through from "WAHP", above, to "Peak Performance".
And I attribute most of that to Maury Hurley. The guy was a martinet and rather an ass, but he was a damn good TV producer. Gene told him his vision and Maury made sure the writers adhered to it, no matter how "wacky doodle" he personally felt it was. There was a high rate of turnover among the writers during those first two seasons because they were pissy at getting "rewritten by Maury". I've seen some of their first passes, and I feel he was right more than he was wrong. *shrug*
There was so much BTS drama, though. He was the one who fired Gates because he felt the character and her performance of were both flat, and brought in Diana Muldaur's Pulaski. Because of the circumstances, there was always friction between her and the rest, even though it wasn't her fault. I... have many thoughts.
But Maury eventually got fed up and quit when Gene kept contradicting his own directives to him from earlier -- said "If you can't keep this straight, I'm out!" So he did. After that, TNG just gets so bland for me. There are some darn good episodes in there, but I don't really feel the urge to watch most of them. Gene started pulling back during the third season, due to his failing health, and by the time the season ended it was the Berman and Pillar show. Rick Berman's a Hollywood chameleon -- good at rephrasing things crative people say to him so they think he gets their vision and he stays employed -- but he's had very few actual ideas himself. And Mike Piller was a good writer, but needed someone over him.
The less I say about Ron Moore, the better.