I have used both Samsung S4 and as well as Samsung S5 which is my present smartphone. I just love Samsung S5 the way its touch works.
It works on android platform 6.0.1 marshmallow. And features like multi window tasking and U.power saving which I rarely use but they are good. Most of all the camera is mention-able 16MP camera takes awesome pictures and can even take 1080HD Video recordings. Simply! Awesome it is. Over all the phone is fantastic.