I did not cast my vote. The reason behind my choice is that the answer greatly depends on the genre of your game (and other aspects as well). JRPG and Western RPG are completely different and, depending on which one you are aiming for, game-play can be more important than the story or not.
I would have definitely voted for game-play if your poll had a "great story with bad game-play" option, because decent game-play is a
condicio sine qua non for all games. What I mean is that the game-play cannot be bad, otherwise it would spoil the fun, and if you have to spoil the fun with a bad game-play, there are better medias to deliver a good story.
The same goes for the story though. There are so many games around, with so many different features. If somebody wants to play a game with those features disregarding the story, there are many ways to do that. This is the reason why a story has to be at least decent (by story I mean main plot, lore and/or characters).
If we assume that both aspects are at least decent, I think the main difference is what you want from your game. Of course, a JRPG usually has more story than a Western RPG, so I would say that story is more important in that situation, but that relies on the fact that Japanese uses ideograms, which allow you to convey messages in a whole different way. Doing the same with a language that uses latin characters is tricky, and that is also why JRPG developed in that direction.
Is your game about narrative or fellowship? Go for the story. Is your game about challenge and discovery? Go for game-play. There are other ways to handle this, of course, but if you want to research deeper on this subject, I recommend reading
"A Formal Approach to Game Design and Game Research" by R. Hunicke, M. LeBlanc, R. Zubek. It is a good document that summarize the concepts behind the MDA Framework. I do not know if you already know about it, but it might greatly help you. Of course, you can check the references if you want to go even deeper (they are very interesting).
I think that following that framework really gives you a better perspective than just "doing what your guts tell you" (as I have heard once in a video).
EDIT: as a side note, you could check
one of my posts in another thread with a similar poll. The post contains a mathematical analysis of the reasons why game-play cannot be bad. It adds nothing to this topic since you already mentioned an "alright game-play", but it can be helpful when it comes to understanding my point of view.