I voted for the i5 to use for gaming, any general purpose/computing and what not should be with the i7. This isn't a simple choice by any means, I have never owned an i7 grade CPU, so I have no personal experience on what they are capable of, worst case scenario comparison would be the FX-8350 which I do know how it runs, and the i5 leaves the FX-8350 in the dust any day for single thread gaming tasks, on the other hand newer DX11 titles do like extra cores so the FX-8350 comes a lot closer, but still just doesn't cut it. The i7 could run better than the i5 in some games though.
IMHO gaming wise i5>i7 and for whatever else you want to use extra threads i7>i5 since we're still stuck with DX9/DX11 games. This will change in the near future so, yeah. There ain't no safe bet at this point. Gotta stop repeating myself.
My analysis here has gone like this: Personal experience>People's experience>Review sites>Random forum
Reading 5 years worth of tech material when unregistered does pay off sometimes, but I am unable to throw ideas back and forth,
anyway.
If memory serves, you shouldn't have any problems gaming on both processors right now. If you want to try and "future proof" and with CPU's that's easily doable. Using the i7 does seem like the better option. I am conflicted between the two because of the DX12 hype. Curses.
Personally I am sticking with playing DX9 titles, which usually have abysmal multi-thread/HT support.
At the end of the day, it all depends on what you're going to do. Planning ahead might help.
Your last post seems to indicate that you have already chosen what the systems configurations will be. And I believe that might be the best course of action.
Edit: I'm going to follow this, hopefully you'll throw in some real world gaming comparisons because that is what I am interested in. Benchmarks are way too controlled and don't reflect typical scenarios right.
I'm trying to keep my friend off buying an i7 3770 when he really doesn't need one. I would just sell him my MB/CPU combo, if I had enough money to upgrade to something better.