1. Gameplay (doens't matter how good the story is... if it feels tedious, slow, or boring I will put it down like Lost Odyssey haha)
2. Story (very important for making the gameplay worthwhile over extensive plays as it does get repetitive)
3. Sound (is an important asset to all games, but for the long ventures you take in an RPG it is a must to have a good one... no one wants bad music for 50 hours)
4. Presentation (game needs to take itself seriously without being too serious haha. One of the great things about RPG is it can be so many things without being anything which is why I love them so much. Needs to also have a graphical style that fits the atmosphere like any other game)
5. Replayability (least important out of all of them but main importance comes from the length of a game. I don't wish to play any RPG that doesn't take a long time to beat the main story. You are building a character, team, story, or entire population at times. It needs to have length. But for playing more than once, not as important because it's all about the experience.)
I personally prefer JRPGs over that of WRPGs but of course I don't play as many RPGs as other. Only reason, though, I probably consider WRPGs in the mix is due to Bioware haha. But for now, JRPG is my choice.