Personality does play a pretty big role in a protagonist so I will have to go with this. One big example is Tidus from FFX. I despise everything about him. Despite his "quick hit" hax and overdrives. They could not redeem or save his character in my eyes. Then again a characters gameplay aspects would be dependent on the battle system of the game. I would hope it played well and we can still have a good main character.
"Not on my watch Monsieur Napolean Bonerhard!!!" -Tink [Yoshida designs > Nomura designs]
I'm ashamed to say this, but looks matter to me the most. That's why Tifa is my favorite Final Fantasy character. Personality is also nice but most of them tend have generic personalities. Gameplay is good, too.