(I've added the following in an edit because I realize that my answer isn't very useful without additional information.)

My best friends actually didn't start the company with me, they happened to be some of the very first key people hired by the company--I didn't know them before that. In our startup, there were ups and downs and definitely challenges to overcome; in that kind of environment one really gets to know people's character and I was lucky enough to make friends with two really great guys. Additionally, I got to know many remarkable people this way.

Years after the company was sold and all of us had gone our own ways professionally, I was on a second date with the woman that I am now married to. We were headed to one of her friend's house for a party. While walking up to the front door I asked for the names of the people I would be meeting (to make it easier to remember their names). To my surprise and my wife's her friends were the wives of the CFO and the COO from the company before we sold it. Today we enjoy seeing them socially and even vacation with them from time to time. So it's not just my very best friends that came from the startup its actually many friends.

Some people from the company I'd like to see more, but understandably, there are also people that I usually avoid.