For the past 3 years we've been pulling an 18' Aluminum car trailer that weights 1,350lbs (Aluma). The reason for the car trailer is my street legal car that we race cannot be flat-4 towed. We just recently picked up a new Ford Focus that can be flat-4 towed and we're installing the parts right now (e.g. baseplate, light wiring, braking system, etc.).
One advantage of a car trailer is you don't have to worry about what car you choose. However, there is a little more work to load/unload the vehicle. One advantage of a car that can be flat-4 towed was mentioned above - for most vehicles it's a quick connect/disconnect.
We've got the car trailer load/unload down to under 15 minutes, which includes a triple check check-list routine. We race on weekends so we load/unload on Friday, then repeat on Monday. However, on non-race trips, having the new Ford Focus that can easily be connected/disconnected would pay big dividends on trips where we want to park the motorhome, see the area via the car, then move on - possibly more than once a day.
If I could only have one car - I'd get the one I want, even if it has to be trailered. Luckily, the car we race is mine, and the new Ford Focus is the spouse's ;o)