I chose Ax. He doesn't have the greatest beginning or the greatest end in the story, but apart from liking the idea of being an Andalite, he's got a very stable place in the war. He's rescued by his brother's chosen warriors and is fighting against the enemy to whom he's sworn vengence for killing Elfangor. He goes from being a child, like the others, to being a fighter...but to him that's a position of honour, rallied against the Andalite's natural enemy. And as much as it would suck being cut off from not only your family, but your entire race, he also gets to be the Andalite face of heroism when it comes to the Yeerk invasion of Earth.
And he gets to experience taste for the first time. Cinnamon Buns. Buh-nz.
...incidentally I've never eaten a cinnamon bun. O.o