Answering the topic question: I prefer Coinops because it is very easy to set up - no tech expertise needed. HK doesn't seem that bad, but Coinops appears to be the winner in pure terms of ease-of-use.
My secret dream is a 3D0 emulator, though that's pretty much hopeless. I'd settle for a Dreamcast emu, though I'm going to go ahead and guess that that's technically impossible.