TOS is a cultural icon. A few notes of that one, and almost anyone, trek fan or not, can name it. TNG had a more regal feel to it in my opinion, which from what I've heard was kind of what they were trying to go for with the design of the Ent-D. Enterprise opening theme was a good song, but it didn't feel trek to me. I captured the essence of what many feel trek is about, but it didn't seem to fit with trek to me, atleast not as an opening theme. DS9 and VOY I think had the best opening sequence from both and audio and visual standpoint. Both peices were very commanding, and the cinimatography simply fit the music better then the other shows had been able to do.