I don't particularly think the movies are better than TNG as a whole but they make decent companion pieces. I do however think the TOS movies are probably more watchable if not actually better than the series they are based on if for no other reason than being 20 years newer and much bigger budget
The pinnacle of Trek to me was DS9, which never got a movie, as it was more ambitious with the narrative but I believe the general consensus is that TNG is the best
I've been meaning to rewatch all the TOS movies so thanks for the reminder
PS I find the "New Trek" movies to be entertaining but somewhat hollow