I have and love the HTC One. If you are going to run them completely stock, I would get the HTC One. HTC Has been very prompt with their updates thus far. They have already started rolling out 4.3 for the One, but all the S4's are still waiting. If you are going to get a Google Play Edition or flash GPE ROMs, the decision is much tougher. In that event, the S4 has a superior camera and a larger screen, but the HTC One has much, much better speakers and feels better in the hand. Of course, on the One GPE you get the infamous black bar that you do not get on the S4 or the stock HTC One.