My first purchase was 5 years ago, house hacking with my buddies as roommates.

I will be occupying the 1st floor and will potentially get a roommate within the first couple months.

My roommate, who cosigned with me, wants to stay on the property.

I would like to have roommates in my home after I purchase it and as such, I would like to be able to limit my roommate selection to not allow kids.  

Your roomie also sounds intolerable as a roommate.

I had an engineer roommate once, and she made good money... bought her own house after 6 months on the job after college.

Finding BP recently really gave me the motivation to get the ball rolling, and so I actually just got pre approved for a mortgage.I'm looking to live in a place with roommates to start out but I'm also open to turn keys, flips, etc.

You can choose your roommates, but if one backs out or you do not know them they will place a roommate.  

If you don't mind having roommates you can also look into buying a single family home and renting out your extra bedrooms.

But two things to keep in mind; first, if you buy a plex you can also find a roommate for the unit you live in as well.