my friend is building a gaming pc he is on a budget he is not sure wich build would be better
he will be using 8 gb of ram
his resolution is 1400x900
so which build will be better and give him more future proofing
It will depend on the games your friends wants to play.
Some games will do better with the additional cores (i5) while others will do better with the better video card (boost).
Personally I'd go with the i5 knowing that you're more likely to replace the video card in the future than the processor. You're going to be able to use the next generation video card with either of them - you aren't going to be able to upgrade your processor without buying a new motherboard too (unless you upgrade within the same architecture - IB i3 to IB i5/i7 (Haswell won't work with the IB motherboard).
They will, but those games won't do that much better. I agree with what you're saying though but games today still benefit more from a better graphics card. And plus you can't upgrade either of those processors to Haswell because it uses a new socket. IF the OP gets the i3 they can upgrade to an IB i5 though. Something for the OP to think about.