Thinking back, I dated mostly fraternity guys in college, although my longest relationship towards the end of school was with a non-Greek guy.
Since college, all of the guys I've dated have been non-Greek except for one. My boyfriend now (who will most likely become my husband) is a non-Greek.
Honestly, I think it's who you hang out with. In college, my sisters and I hung out with other Greeks so it was only natural that I dated Greeks most of the time. Now that I'm out of school, most of the guys I've met have been non-Greeks, so that's who I've dated.
I don't really have a preference one way or the other. As long as my boyfriend understands that Greek Life is important to me and is supportive about it, then I'm happy.