It depends on the game and PC. 99% of the time the PC version would be the superior version but I had realised that in this gen, more and more console games are closing the gap to their PC counterparts.
MGS V is a great example, I bought both the Steam and PS4 versions and honestly speaking I can hardly see the difference unless I really take a close look at the PC version (on max setting). Kinda makes me think that spending money on the PC version is a waste.
But most of the time the PC version will be better as there are mods and graphics capability wise it would definitely be better somewhat. The catch is you would need to have a good PC or constantly upgrading your PC every 2~3 years for getting the max settings for most games.
MGSV looks stunning on PC and has a nice array of options, but it is in no way an example of anything. The Fox Engine is an anomoly and you can be damn sure not many developers are going to have as flexible and as scalable of an engine as Fox.
The gap is not closing, it's greater than it's really ever been. At this point in previous lifecycles, I don't think you could buy a midrange card (like a 970) and completely run laps around the consoles. Again the developer hesitance to move away from cross generation games is a reason why this hasn't really shown itself yet, because those games still must run on ancient hardware.
I know people say you "have" to upgrade every 2-3 years..but isn't that the point? I guess you could settle for less, but in that amount of time I'd want to make my setup more current and try to get the most out of my game instead of compromising.