How do I make this choice?

I am dating a guy named Jake, but he's being too serious. I have a feeling i'm going to need to break up with him. I really like one of my ex-boyfriends named Devon, but he can sometimes be a bit ignorant. There is also Devons best friend, Emmett. I've liked him for a while, and I think that he may like me back, but I can't be sure of anything at this point. Finally, there is Mike. He asked me out and then changed his mind, and I knew that he liked me. Now I like him, but he says he has a girlfriend. What should I do about this?