I'd say it was KH. KH is more mainstream with the Disney tie-in. I've never even played a Tales game and I'm much more into RPGs than the average gamer. Unless you are specifically talking about Western RPG fans being more into action-RPGs. If you are talking about the general audience, then it's KH.

Though for me it was Secret of Mana.

Also, though it's not an RPG, I wouldn't discount the influence of Symphony of the Night on this genre. It has many RPG elements like equipment, spells, and levels, and it introduced a lot of people to those elements.