I personally see no reason to buy anything more than a PS4. I have a PS3 and it plays all the same kinds of games I'd want to play on a 4 or 5, with similar graphical fidelity. I have a 4, but only really have used it to play a remake of a game I can already play on the 3. I also have a vita which is used for indie games since that thing has nearly every indie game you'd ever want to play available (either officially or via homebrew)