Honestly for me TNG, VOY, DS9 all had their "bad seasons" and they all had "great seasons" It is too hard to pick a clear winner Overall all three were enjoyable .
Throw in Enterprise into the mix and you had 4 great series overall. What killed Enterprise was the initial two seasons. I used to hate the show, then I decided to finally watch it, it was much better from season 3 onwards.
The two new series haven't started great but I will give them the benefit of a doubt to correct their ways so to speak kind of like Enterprise did.
I gave up on Enterprise and DS9 when they were initially aired. The first season is a slog in both. I rewatched them a couple years ago and Enterprise is the clear winner. DS9 keeps going up and down and ends in nonsense.
I watched Discovery, more in amusement how bad it was than for finding any redeeming values. I doubt Discovery can correct its ways, it has strayed way too far from the Star Trek values. Picard had a good initial episode(s) but makes the same errors as Discovery and Picard has become a very annoying character.
Btw what happened with that other show, The Orville. It disappeared.
What killed Enterprise is the intro, wrong music. Thanks Netflix for skip intro, made it 100x better.