Listen to my heart or brain? Who should i chose ?

I have 3 guys who like me right now, one is my ex, we were together for 3 years, 2 years ago we broke up, and he wants to get back together now. i still have lots of feeling for him and i feel like we are a good match. The second one is a old friend, he is currently studying in another city but he recently confessed his feelings for me, leaving the situation completely open. i feel like he could be better because he is very smart and we could have a stable future together. Then the third guy is a guy from my class, he is super good at every he does, straight As and always a charmer but im not attracted to him at all, and i don't have any feelings for him. i feel like the logical thing for me to do is to chose the third guy, or the second, but my heart tells me to go back to my ex, because i still love him.. my brain of course, says no to that. What should i do??? Please help!