Nightcrawler, hands down! I'd get to climb on walls, teleport, have three fingers, grip things with my tail (and therefore eat from three cartens of icecream at once), man, it'd be the coolest thing ever!!!!!!!!!!!!!

What would you do if you woke up one day and realized you were back in middle school (if you are in middle school, lets say elementary school along with what are you doing on this site?), but with all the knowledge you have now?