What martial art should i take?

Brazilian Jiu Jitsu or May Thai (or another fighting style of your choice that you think would be good for me). I wrestle for my school and got 3rd for the championship. I'm 5'8 and 16. I want to be able to know what I'm doing in case I get into a fight withowh someone like at school or something like that and know how to be brutal when on the ground too. Any suggestions? I'm not the guy hat goes around looking for a fight, I keep to myself. I want to learn how to fight because some people like to pick on the quiet guys.