still, core i5. even better with overclock.
however, what is your current rig? are you just curious or want to upgrade? if you have an amd rig and have the opportunity to upgrade to an fx cpu, then the sole cpu upgrade will save you money. if you're upgrading whole rig from a phenom or core 2 quad, then core i5.
Strictly speaking the Intels are faster but having like built many gaming rigs you won't really notice anything if all is higher end.
Been running a X6 1100T/8120 with Crosshair V with the new sapphire 7970 6Gb card in eyefinity and the performance is very high end, that said people prefer the comfort of having a Intel. At the end of the day its all your choice both setups are good.
PS: Z77x UD5h, hard pressed to find a better value orientated board, if you want something flashy then the Gigabyte Assassin board is probably the best Z77 out right now.