I voted for Sapphire.
I prefer Ys I & II and Gate of Thunder, and maybe even Ys III, but I have only the US versions of those, so I don't want to vote for them in a PC Engine game poll.
Same story with Galaga, Parasol Stars, and Space Harrier, but I wouldn't vote for them anyway. I do have the JP version of Cadash, but it's not exactly best game ever material, in any language.
Puyo 2 isn't even as good as the first one.
Bazaru is a lot of fun, but I completed it once and probably won't look at it again for another few years. Sapphire offers better replay value and is more rewarding.
I'm a Kaze Kiri fan, but there's no way I'm voting for a souped-up Kung Fu as the best PCE game of all time, no matter how impressive it is.
Rondo is cool, but terribly overrated.
Daimakaimura doesn't really belong in this poll.
Kato and Ken is garbage.