My friends are driving me nuts with relationship drama! Advice?

It appears that I am playing relationship counselor to some of my best friends: So my friends used to date each other, but broke up almost two years ago. They were able to remain friends, because they were friends before. Its been obvious though, that they are still attracted to one another, and care about each other.

In the beginning the girl broke up with the boy after dating for a year. She's confessed to me that she was being impulsive, and shouldn't have done it. She tried to get back together with him, but he said no (which I think was good as it gave them both time to cool down).

Then the boy decided to confess his love for her, only she turned him down because she was dating someone at the time. They both dated other people over the years. Now after a few years, they're both single again.

They've both confessed to me that they still like each other, but aren't sure if they should ask the other out. I'm not sure which one should ask the other out though (being a friend to both of them, I'm supposed to miraculously know the answers lol).

Who do you think should ask the other out? hey, if they want to give it another shot, I don't think it would be a bad idea, as they've both grown up since then, and are still very compatible for one another. They've never had the "friends with benefits relationship, and their relationship was very good when they were dating.