ORC by far, but I'd probably say RE 5 if only due to the boring level designs and the s**** final boss fight. RE 4's story was absolutely terrible, but I still enjoyed it a hell of a lot more then RE 5, even though it really didn't feel all that much like an RE game.
When facing a zombie apocalypse, don't join up with a group. Why? Because you'll end up blowing your own head off due to all the pointless drama caused within.