Well, its odd that you use your phone for that instead of a tablet but id think the HTC One M8 would be best for that if you want better sound.
1. If I'm going to own a 'phablet' then it greatly diminishes the need I have for a tablet. I gave my iPad Air to my Mom.
2. I usually do all this laying down in bed, so a tablet is really uncomfortable to use.
I love HTC Phones but the M8 is isn't the latest and greatest so the tech side of me would be annoyed. If only the M9 was coming out soon.