You should be able to play BF4 on high @ 60 FPS. (If you have 8 gigs of RAM.If you have 4 however,then you will be able to play it on minimum
😛)
If you don't do video editing,then get an i5 4690K.i7 is useful when video editing,while the performance increase in gaming over the i5 4690K isn't big,maybe like 5%.
You can get a much,much more powerful GPU to pair it with your CPU.
But if you're on a tight budget,then the 750 Ti will do just fine.