Forget about all of them and find a new guy.
Nah, I know that isn't a choice you're likely to take, so I'll give you some other advice.
Leave Chad alone to work out his issues. Either break it off completely, or at least tell him to come back when he's NOT taken.
I don't advise getting into anything at all with the friend from middle school. A) He obviously either has commitment issues or is not over his girlfriend,
If he is still with his girlfriend when you try to pursue him, he's just going to end up like the situation with Chad. Personally, I wouldn't touch that one with a ten foot pole.
As for the third guy, I'm not sure what I should say since "came on too strong" has a pretty wide spectrum of definitions. If he seems to mean well, it doesn't seem like too bad of an option.
But of course, this is my opinion just based on what you've told us. I may not be accurate, and you're welcome to take my advice or to leave it.