Hey PyroRaider,
I'm currently running a GTX 960 and let me tell you what happened 1 week into installing my shiny, new gpu into my rig - I got avalanch-ed in a wave of of buyers remorse. After a quick trip to Tom's Hardware (http://www.tomshardware.com/answers/id-2649985/sell-gtx-960-purchase-gtx-970-simply.html), I decided my 960 was good enough.
What's my opinion five months after my initial purchase? A calm acceptance of what could have been, while enjoying what I already have. At 1080p, 60fps gaming, a 960 will NOT tear up new grounds. Your gaming experience will be playable, enjoyable even, but it will not be ULTRA/MAX SETTINGS. A factory-OCed 960 can achieve pretty good settings tho, and if you're not easily bothered by lowered graphic settings, than a 960 is good enough for you.
The thing is, how big of a difference is the 960 and 970? Personnel recommendation from someone who owns a 960: get the 970. It will achieve more for you, at 1080p gaming. It should be able to achieve stable 60fps on all demanding games at one-setting-below-max.
Will a 960 play Skyrim, TF2, L4D2 well? Yes, yes, and yes. Will a 970 do even better? Hell yeah. However, it does depend on your budget. A 970 and a 960 is a good 150 dollar price difference in my country, and to someone with a budget, that's still a huge difference. If you are willing to pull out that extra cash, go ahead and invest in a 970. It will give you far less buyers remorse, it will give you a greater playing experience and it will future-proof your system for a lot longer than a 960 can. What if you're not willing to put in the extra cash to jump to 970? It's okay, it's absolutely okay. A 960 will still perform very well at 1080p. Main difference between the two GPU's here will be in terms of investment - how long do you want that card to last?
Will you be playing more demanding games, like Witcher 3? You can forget about MGS5, it's so well optimized, a five-year old GPU can run it. If it's a yes to Witcher 3, the 960 and 970 will both give you playable experiences, but the 970 will bump the graphics quality much higher. If you aren't going to play those types of games, and if you're satisfied with average-graphics (nothing wrong with that!), a 960 is good enough.
It's all up to you, but again, I personally recommend the GTX 970 because say you do decide to pick up Witcher 3 or Dragon Age: Inquisition, or hell, Fallout 4, 'cause they are on sale, you will definitely not regret having bought the 970.