I just got the HTC One yesterday after using a Nexus S for the past two years. So far I am extremely happy. It is very fast and despite what some reviewers say, I really like the feel usability of Sense 5. The speakers sound superb. The phone build is great, but very slippery. I was so nervous taking it out at first. My girlfriend likes it so much that she wants to sell her Iphone in order to get the HTC One.
So if you want something other than the Galaxy S4, I would recommend this.