Hmm.. I think it's very dependent on what "the job" is - ie, finding the right tool for.
I'd say a smaller car with a towbar probably has the most flexibility. The tow ratings in Canada and I believe the US are way below those in the UK, but I think there was another thread with someone putting a home made hitch on a Civic or Accord or whatnot.
So probably something like that. A Civic or Corolla with a hitch; perhaps one step up. Or, even better from my perspective - a Matrix or Vibe. Hatch > boot any day!
(Boot = trunk, tow bar = hitch - except a towbar really is the bar onto which you attach the trailer, the hitch is what the bar connects to, but ANYWAY!)