That's a pretty broad request, but if it were me I'd be looking for a low mileage car that looked like it had been well cared for. You can usually spot that right away from the exterior appearance alone both inside and outside. If both are in reasonable shape for the age of the car there's a good chance the previous owner had some pride in the car.
Look for evidence of mods under the hood as well such as wires etc that shouldn't be there. I'd personally stay away from something that had large wheels because the brakes and suspension take a hit from that. Of course if the car was returned to stock that might be difficult. A test drive should tell you is there was a problem in all likelihood.
I'm not saying a rental car would necessarily be a bad choice, but you'd need to find out for certain if it was. There are many base models out there on the market by now. That could influence your decision.
Like I said, your question can have so many variables. The above are just a few.