If you're just gonna use your rig mostly for gaming and not for content creation, getting an i5 would be sufficient for your usage. Most games don't utilise more than 2 threads on your CPU, when the i5 already has 4 and the i7 has 8.

If you're really making a budget GAMING rig, get the Intel G3258 and overclock the s**t out of that chip. On a gaming level it loses out slightly to the i7 4790k (also overclocked). (http://www.youtube.com/watch?v=evXpqpNhu_Y)

Use the money you saved for a BEAST graphic card, THAT will improve your gaming experience by a LOT more.

Lastly, don't cheap out on power supplies. Get a good quality brand and give a 100W or 200W headroom. Meaning get a 600W PSU even if your system only needs 500W. If possible try to get 80Plus Gold rating and above ones to be sure you're getting steady power delivery.

All the best in your rig!

Personally, I'm quite the nVidia fanboy and don't read up much on AMD cards.

But from what I read the performance boost from R7 260X to R9 270 is quite massive and the price jump is about RM300.
From the nVidia side, the GTX 750Ti underperforms both cards and the GTX 760 is VERY expensive for the performance.

So I would suggest getting the R7 260X, the R7 265 or the R9 270, whichever fits your budget better.