PS4 pro

Well, you might notice an improvement on the GUI and OS [faster/smoother but might as well be just my imagination] and you need a [full] 4K Tv to notice any difference on the graphical aspect.

Please feel free to post any questions pertaining the PS4 [Phat/Slim/Pro] in the following forum --> playstation-4 don't worry about the language barrier since most of the people here write only in Spanish, you WONT be criticized or ostracized for speaking English or any other language, we're open-minded, like to help each other and language is "of no consequence" here

IMO is not worth it unless you own a 4k TV, the graphical differences are not that big. You'll get more effects and more stable framerates on certain games and 4k support