Recommended PSU for R7 360 is 430 watts with a 6-pin PCIe power cable.
300W PSU is like minimum for GTX 750ti, for the sake of some other powerful components you might be having & for worst case scenarios you should provide atleast 100w of headroom. So a 400W PSU is suggested.
That being said. These are quality Power Supplys. If you can figure out which power supply you are using it would be helpful.
Personally I wouldn't buy either and save 20$ more and go get a GTX 950 EVGA SC+ for $130 from fry's with a $30 rebate I think. http://www.gamersnexus.net/hwreviews/2051-nvidia-geforce-gtx-950-review-and-benchmark/Page-2#!/ccomment-comment=10003360
^(this is why)
But if I had to choose I would still go for the GTX 750ti