Wear whatever makes you the most comfortable.
Kids might start making fun of you for it in middle school so if you are that worried about getting teased and bullied I guess around then.
That being said, I've switched back to tighty-whities since they are much more comfortable and if someone really cares that much about what kind of underwear I am wearing that is their problem.
most dudes still wear tighty-whities so actually you dont have to wear boxers it just that most prefer boxers over tighty-whities because thats what most young children wear...thats how i feel but i think briefs and tighty whities is almost similer it jst a mix of boxers and tighy whities
When you feel more comfortable in boxers, I suppose.