In my opinion, the GTX760 is better than the R9 270x although the difference is not necessarily huge. The i3 4130 is a little better than a stock FX6300, and they are about even when the FX6300 is overclocked. Overclocking the FX6300 costs extra and then would be considerably more expensive than the i3, which is why I recommend the i3 over the FX6300 in the first place. The i5 is ideal if you can swing it. I like logainofhades' 2nd build although I would try hard to get the i5 4440 and GTX760 if I could.
PCPartPicker part list:
http://ca.pcpartpicker.com/p/3hrLU
Price breakdown by merchant: http://ca.pcpartpicker.com/p/3hrLU/by_merchant/
Benchmarks: http://ca.pcpartpicker.com/p/3hrLU/benchmarks/
CPU: Intel Core i5-4440 3.1GHz Quad-Core Processor ($195.00 @ Canada Computers)
Motherboard: ASRock B85 Pro4 ATX LGA1150 Motherboard ($78.00 @ Vuugo)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($76.36 @ DirectCanada)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($64.75 @ Vuugo)
Video Card: EVGA GeForce GTX 760 2GB Video Card ($269.04 @ TigerDirect Canada)
Case: Antec One ATX Mid Tower Case ($49.98 @ Newegg Canada)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($54.99 @ Canada Computers)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer ($16.79 @ DirectCanada)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($95.88 @ DirectCanada)
Total: $900.79
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-03-27 14:05 EDT-0400)