If we were to extend this discussion to cover incidental music, I would have to say TOS wins quite easily, followed by TNG in a very worthy second place for seasons 1-3 (and some of 4). After that unfortunately, the dreaded Trek Muzak virus sets in for subsequent incarnations - with much of the output in hitherto unimaginably bland territory. Far from "not calling attention to itself", as I believe Rick Berman once proclaimed - the sheer, unadulterated vapid insipidity of it would always have the polar opposite effect on me!
As for the movies, the first ten have some amazing scores - ranging from, minimally, extremely good, to towering, truly inspired masterworks (take a bow TMP). I do like Giacchino's music a lot as well, but for me, they're not quite on a par with their predecessors.