Next: Nokia Lumia 930
Current: Samsung Ativ S running 8.1 Developer Preview
Previous: HTC HD 7 (died shortly before release of 7.8)
Mind if I ask in what way your 720 is not enough for you? If you aren't already running the 8.1 preview I highly recommend doing so before making the decision to buy a phone of a different OS. If feature parity is your concern, 8.1 is liable to solve that, and they're is literally no coast involved in getting the update. Some users have complained about their battery life taking a hit, but not all (mine is actually better post-update) and the 720 already has stellar battery life according to reviews, so even if you're took a small hit you'd still likely be alright... In fact, there are aspects of this update that leave IOS far behind feature-wise.