Ah, good question. I just had to make a decision about this a few weeks ago when I made an offer on my first property.
I initially told my agent that I only wanted to see properties that were fully rented. I wanted to use the rental income in addition to my own income to qualify for a higher loan. I then realized that since I was doing FHA and needed to owner-occupy I'd have to evict someone in order to move in. That did not sound appealing. Plus, I wouldn't get to choose my own tenants.
My ideal situation would be to find a 3 or 4 unit property that has one or two units vacant. I wouldn't have to evict anyone, I could choose my own tenant if needed, and I'd have minimal other tenants that weren't of my choosing.
I ended up making an offer on a vacant triplex--go figure. It was in immaculate condition, totally move-in ready, right across the street from a huge medical center and within 2 miles of the nearby university. While I'm a bit stressed about finding tenants once we close, I'm pretty confident that I'll find some good folks from the medical center or the university.
Feel free to write me if you have more questions. Best of luck!
Erin