After getting my priest most of the way to level 15 by exploring more dangerous areas, I've changed my mind about what class/race to use for my Alliance test. My priest is finding it harder and harder to explore, and bubbling & running doesn't last long against mobs 20 levels higher.
A rogue can sprint, and sprinting doesn't having problems with scaling the way bubbles/healing does. If I can run away fast enough, I can live. The gnome racial ability of escape artist helps, too.
As a level 5 gnome, I'll be able to use target dummies; level 10 doesn't give me any immediate improvement over a non-gnome, but at level 20 I can use (but not make) a Goblin Rocket Helmet, unlike non-gnome engineers. I could also make a Gnomish Battle Chicken (to act as more of a decoy) if I need one.
A pacifist rogue is also more obvious in an armory entry...
Finally, due to what I've found about exploring XP, I should start the character around a holiday that allows low level characters to earn a fair amount of XP; this will allow me to maximize the amount I get from exploring.