Search Results: he is scared from past relationships

After 2 long years of failed dating situations I am in a position with a few guys that I can possibly see myself getting into a serious relationship with. I'm at an age and a point in my life where there's a good chance my next boyfriend will be the man I marry so this choice is freaking me out and obvi the choice is up to me but maybe an outside perspective can help... Who should I pick and why?

A)I was dating this guy 3 months ago & we started to fall for each other fast and instantly had great chemistry & everything was happening way to fast (like exclusive after 3 days of knowing each other and hanging out every day)... He backed off from us, told me he just wasn't into it & I even said to him I think we moved to fast and your just spooked but I know you didn't actually stop liking me... A month later I was right.. He started contacting me again. I told him I wasn't feeling it if he was just going to back off again... & he has actually been showing interest since... we've hung out again after & I know he likes me but needs to move slower than before which is totally understandable. He def has the look I go for and we are very comfortable with each other and can be ourselves.

B) I actually haven't even met this guy yet (it's through online dating) but we've been talking for a few weeks and he's awesome, we're so much alike in so many important ways.. Only reason we haven't met is because he's a surgical med student and I'm also in grad school and we have both been crazy busy with finals over the past few weeks. I feel a connection and we make (mostly him because he's the dude) time to call each other and be in contact like every other day.

C) OK this one I have the most on the line.. We even have a marriage pact.. he has been a close friend for 10 years, he has always admired how silly and playful I am (guys either 100% love this about me or grow to resent this about me) and is the only person I know who is actually funnier and more original than myself but does it the same way that I do and no one else has ever been able to meet me at that level (we use to and still do play awesome good hearted pranks on friends and just come up with silly ideas and we're both the life of the party on the dance floor. He's gotten even better looking with age(he's also incredibly smart and in med school in another country by choice and I'm visiting next week.. he is also moving back near me soon). We have met each others families and they want us to be together ha. We've kissed etc. already and had serious talks about starting a relationship (which would be this spring/ summer), it scares me to date him because this can either be the love of my life or I lose a great friend.

Who do you think I should pick? What should I do?