Which fight style should i go for?

i am currently 20 and a very skinny guy, im 6'3'' and 165 pounds. Once i gain a little more weight, probably around 180 pounds i want to take up some fighting cles for self defense and as a recreational hobby to keep me in shape. I dont have much fighting experience except for karate and tae kwon do when i was younger. I want to get into mma, which fighting style should i start with?