The "Win8.1 is faster for gaming" meme is mostly a myth. Maybe if you have an AMD FX CPU, and play BF4 exclusively, it's faster. But I've seen comparisons made with other CPUs, and Win8.1 was actually slightly slower than Win7 in some games. So it's definitely a mixed bag.
I prefer the UI of Windows 7 myself. Operating 8 or 8.1 is kind of like playing a video game.
Move mouse cursor here, swipe downward there, hidden menu pops up, quickly click the item you want before it disappears, etc.