I feel the same way about TUC. To me, it's one of the weakest of the TOS films. I can't buy in on INS, though....that's the only film in the entire franchise I actively dislike.My controversial opinions:
TWOK would be middle to the lower end for me when ranking the films. It has its strengths but for example I prefer watching INS.
Sisko and DS9 are good but not the best Star Trek because they don't portray the positive future I want to see. Into the Pale Moonlight is a brilliant episode but also not Star Trek to me.
I'm the opposite. I like Star Trek with an edge. It can be edgy and optimistic at the same time, which I think DS9 pulls off nicely, but pure roses and sunshine don't interest me nearly as much.