The way I understand it, it's pretty much a tossup between the S4 and the One which one is The Thing right now. It probably comes down to personal preference in the end as they're pretty evenly matched. The iPhone is a viable contender as well if you're not an Apple hater - they're always a safe bet to be pretty awesome.

I'm getting a new phone soon too, and I'm leaning towards the One mostly because I much prefer its design, but I certainly wouldn't say no to the S4 either. The One's speakers are a plus for me too as I've always had a problem with low volume when showing youtube videos to friends or whatever.