A controller for PC, is it worth it ?

As you may have seen, I'm taking a slow walk toward console gaming. For an almost exclusively PC player (until now), the prospect of switching from mouse/keyboard to controller is a bit daunting.

As all PC gamers, I've often suffered the plight of badly ported console game, and their....peculiar (if not another less polite word) controls. Until know I've soldiered on and stuck with my trusty companions. But know, on the eve of my first entry in the console world, I'm pondering purchasing a controller to gradually accustom myself with those strange contraptions.

That being said, what is your opinion : Is a controller worth it for games like Tomb Raider, Akham Origins, or Assasin creeds Black Flag, or should I stick with the M/K of yore ?

(obviously the RTS, FPS and such are excluded from that paradigm: I'm not mad !)

And if you were to recommend one, which would that be ? Does the wirelessness of the PS4 bluetooth controller overcomes the native support of the xbox one ? Are third party controller more interesting than first party ones ? Is the hassle of setting up the PS4 outweighs it's wireless prowess ?