Things that sell well.
Sex
Asskicking
Simple
A blend of dim and bright
Bloody
Ayla fits most of that(just not the last one). No one's sexist against Ayla at all! She's pimped out!
Ayla is also the character doing the worst in this poll. I think the facts do not support your opinion. Also--and very significantly--from among the people who have bothered to write about their choice in a post, Ayla consistently draws the most criticism, apathy, and disdain.
People are jealous of her goods.
But, Ayla mainly since that was toward the start of the poll before anyone took into account the whole plot driven thing V brought up. Ayla just doesn't quite as much for her character is what it is. If that's a fault on anybody's part, creators since they added less things for Ayla. The least backstory(not to mention story altogether). Her character keeps changing with design(club to fist WTF) and she's the only one who has no special story for herself. It makes sense for her to be in last when you consider no one had thought of plot driven yet.
And when you take the plot driver into account, Crono and Marle make the most sense. Crono just doesn't have quite as many votes for 2 reasons.
A.) He's the main character.
B.) People already dealt with him dying so it couldn't be found as quite as interesting as one of the other party members dying(which sounds kinda gruesome).
Marle fits the ticket.
As for the others, not really as many votes. People either don't see any reason for the loss of Lucca, Frog, or Robo, or they just get a lot of love.
Magus, i don't know. There isn't any plot driving and he's got everything I mentioned Ayla lacking and more. So why he suddenly is gaining a huge amount of votes is beyond me.