As far as the HTC One vs. S4 I'm in the same boat, trying to decide what phone to get. I have spent some time with each of these phones so I have hands on personal experience. I'm leaning toward the S4, here's why
S4 benefits
1.Removable battery 2.micro sd card 3.Software/firmware updates ships with Android 4.2.2 4. The look of Touchwiz along with features have improved, I don't not like Sense 5 or blinkfeed. There is some flaws in how Sense runs but I'm sure they will fix the issues soon. The S4 is easier to fix and more durable, just wait I guarantee there will be problems with the One, people complaining about scratches on the screen (no Gorilla Glass on the One) and the body. The S4 has very durable plastic, that I will have a case on anyway and Gorilla Glass 3. The camera is better on the S4 unless you take a lot of pics in the dark, in that case I ask, why do you take pics in the dark? I lost count of my nuber listing system but I will keep going..... The S4 actually feels good in the hand, in my opinion a lot better than the S3 and my goodness is it freakin light. Balancing weight throughout the device has a huge impact on how it feels and I think Samsung did a very good job with this in the S4. Like with my Nexus 7 I can take two fingers and balance it easily because the weight is even. To me the benefits of the One are it looks great, and has loud speakers, but the S4 is plenty loud for me, all I would use it for is navigation and listening to a podcast every once in a while, I have big speakers on all my devices or headphones for anything else. To me as much as everyone says about how gimmicky Samsung is with their software, I feel thats how HTC is king of with the Beats speakers or the 4.0 megapixel camera. I'm sorry Megapixels don't mean very much in photography but 4 is not enough. I heat the Ones battery life is not good either So there is my little review/ HTC One bashing, but honestly I'm not 100% sure if I want to get the S4 over the One.