One quick fix would be to combine the two Windows stores. For example, on the W8 store, Comixology is available, but not on WP8 (would be great on the Lumia 1520). But anyways, as for apps I'd like to have:
1. A music locker like Google Play Music (one that doesn't use OneDrive space. Space is limited already, I don't want to use up more of it. A 20,000 song limit like on GPM would be much better)
2. A wireless syncing app like AirDroid (extremely conventient)
3. WatchESPN
4. mxplayer
5. Press
And an extra thing I'd like, the ability to play FLAC files