If you could have any vehicle (a helicopter, sports car, space ship, yacht, etc.) and a free place to park it, what would you choose, and why?
Do I just not get these questions, or something? Because I can't for the life of me think of a reason why anyone wouldn't instantly answer "space ship", since that's right there in the question, or "starship", if one feels that there's a distinction.
It just turns into a question of what kind of starship. A big ship like Enterprise or Galactica has a lot of advantages: absurd amounts of room to live aboard, and a whole lotta guest rooms. A classic tramp space freighter like the Millennium Falcon or Serenity is a bit cozier, and doesn't need a small army to operate.
This in turn does suggest reasons to pick a more modest or mundane kind of transport: the question as asked only hands you the vehicle and pays for parking. Maintenance, crew expenses, registration fees, and fuel are all out of pocket—and if you think gas prices are bad these days, check out what anti-matter's running these days.
Of course, a lot of those considerations apply to mundane-but-immodest choices such as, say, a yacht, or a submarine, or the Queen Mary ... .
Still ... if we're sticking to single-planet transport, and the parking is free ... I've always wanted a dirigible.