I hate pop because:
1. Most of the "singers" that sing in pop cannot sing
2. The rhythms and tunes are re-used a trillion times over
3. The actual meaning behind the vocals is usually stupid
4. Most of the music is doctored to seem better than it should (for reference, see: this "perfect" metal band [http://en.wikipedia.org/wiki/DragonForce]
5. The culture behind pop is just really sickening as a whole
In metal, electronic/trance, classical, etc. whenever you try to auto-tune something, it is usually for effect, and not the whole fucking song. And you know it is there, because they use it ironically for a phrase, or the music/singing suddenly changes. Metal bands that use auto-tune sound terrible, and most singers that are worth their salt can actually sing (for reference, see: this band where the singers are actually extremely talented [http://en.wikipedia.org/wiki/Linkin_Park].
The biggest difference between electronic/trance and pop, is in electronic/trance, it is made by one person, and they don't try to pass off other people's work as their own. The nature of electronic/trance is to cut up an existing sound, change it, and re-purpose it to sound awesome. Pop just cuts up an existing sound, insert catchy rhythm, and put vocals over it so people don't hopefully notice.
I like listening to music that requires skill to make, not a reckless abuse of auto-tune and drum machines.
Edit: That being said, there are a few pop bands I enjoy. Lady Gaga is awesome, and technically not pop. Her sound is her sound, and only falls into pop because thats what people think of it. I used to enjoy Lights until I found out every single song is about god. I enjoy a couple Katy Perry songs, but I enjoy their metal re-makes more.