It's PCs, not PC's.
Plural never uses apostrophe.
Most common Haswell chip is i5 4690K. Also, i7 4790K. Then, there's i5 4460 the Xeon e3 1231 v3, which is the same without hyperthreading. And their equivalents from pre-refresh (like 4770K).
So which CPUs do you want?
Any Haswell CPU with 4 cores (i5 level) will work as a gaming rig. Full list can be found here:
http://pcpartpicker.com/products/cpu/#xcx=0&f=34,40&C=4,22
i3 CPUs can also be used for casual light gaming, as single threaded performance is pretty much on par with their quad-core couterparts.