"Bottlenecks" are not what I think you think they are. When we refer to a bottleneck, it generally means that the one component is the limiting factor in your framerate. However, there is always a bottleneck or your framerates would be infinitely high.
A better question to ask is, "What CPU can deliver the framerates I'm looking for in the games I want to play?"
An i3 6100 will stay above 60fps in most older and indie games, but may have dips into the 50's or even 40's in newer games, especially multiplayer ones like Battlefield, even when you've chosen graphical settings where your video card could maintain 60fps. An i5's dips will be not be as bad, and will happen in fewer games. An i7 would be better still.
It really...