I think eveyone just likes what they like. The people who like the S4 and Samsung phones have their reasons and the people who like the HTC One and HTC phone's have their's. Last year I had both the S3 and One X.
I initially liked the One X a lot more. I then got the S3 , it grew on me and, I sold the One X. I actaully liked the look and feel of the One X better but the S3 was so versatile and seemed easier to root. I like that I could add extra storage because 16GB was not enough for me. The S3 also looked and felt better than I thought and I didn't mind that it was made of plastic.
Now, I'm really sold on the HTC One, especially after I've played with it in the AT&T store. Like last year I like the HTC phone better initially but this time it's different. The HTC One is so much better than the One X, it's not even close. The whole experience is different and the closest thing I can compare it to is going from a Iphone 3gs to a Iphone 5 (except the software is drastically different also). The phone just looks and works very well. The availalbe storage is a big plus also.
Other than the improved hardware and slightly bigger screen the S4 doesn't seem that much different than the S3. To be fair, I haven't held or played with it for myself so I have no doubt it will be a nice phone also. I don't really care about all the extra features, the look and software experience with the phone are big with me. I never cared for toughwiz and by the looks of some of the vids I've watched, it looks no different than before.
Right now, I don't see how I will like the S4 better but, I may change my mind once I actually get to play with it.