I5s: 2400, 2500 or 3470?

I'm looking to get an i5, as I'm running a G860 with a Sapphire 7870 right now and getting pretty good performance out of it gaming wise, but I'd like more. Would there be any significant increase if I upgraded to any of the aforementioned CPU's in the title?

My main concern is increasing my performance in GW2. I'm playing it at pretty high settings with occasional dips below 30 FPS, and maintaining around 40-50. Have yet to enter into PvP or WvW, but I doubt i'll spend much if any time there anyways, so they're no concern to me. I'll mainly be doing PvE content, like dungeons and such.

::EDIT:: Forgot to mention that OCing will not be a viable option for me at this time. I know that OCing can be useful but at this point in time I haven't a sufficient mobo nor desire to delve into OCing.