My opinions on alton towers' ride/area audio:
Personally, I think nemesis' theme is too similar to a generic 90's horror film music. I love it, and it fits perfectly, but I can't call it my favourite (the ride itself, on the other hand is far from generic and is by far the best ride at Towers imo).
Hex is great, I'd call it a close second. Maybe if they fixed the audio in the vault so a true high quality version could be heard, then maybe I'd put it at first. Fits the ride perfectly, just get it open again!
Spinball Fits the ride quite well. It sounds like a generic video game type music, which is exactly the effect the ride needs. Love the ITHOTMK section to this to. Maybe feels a little repetitive if you've been in the queue a while though.
Katanga canyons music is fun. Creates a perfect family atmosphere without sounding too childish. Suits the theme and target age of both RMT and Congo.
Th13teen isn't my favourite audio. Far too repetitive. I like small parts (the counting for example), but it gives the wrong environment. 13 should be a family thrill ride, yet the audio sounds like that of a scaremaze.
The smiler audio is a strange one. I hated it at first, even now the thought of standing in that damy pit right next to one of those speakers whilst the ride breaks down makes me want to cry. I like it though, somehow, it manages to be sinister and exciting at the same time. Be so much better if it was played a little quieter after the first inversion, painfully loud sometimes.
I like oblivion audio. Does exactly what you expect from the theme. Makes the station seem loud and energetic, highlighting how quiet it is at the top of the drop. Gives a great atmosphere in the station, especially at scarefest at night.
Duel's audio is like... duel. Not too bad, though nowhere near the epicness of the original. Gives quite a nice pace to the ride, though does take you out of the story and just doesn't quite suit scenes like the garden or spider scene (which should have quiet, slower audio imo)
And finally, what has to be my current favourite - Galactica. At first I thought I prefered air's, but having stood by the ride and heard the audio, felt the atmosphere of Galactica, it just felt right. It has the same peaceful environment that air had, and does it better imo. It feels different to the rest of the coasters in the park, and just as Wardley said of air, most coasters try to be the villan, galactica's is the hero, and the music reflects this. Just my opinion on this though, not going to disagree with other people's opinion.