I bought a shiny new 16' PJ 7k car hauler back in 2013. I chose this trailer specifically with the goal of hauling my Jeep, so a 16' seemed quite sufficient.
All loaded up, ready to leave Moab at the end of Easter Jeep Safari:
As happens with this sort of thing, I have since used it to haul dozens and dozens of other vehicles. Knowing what I know now, if I were to go back in time and do it over again I would choose an 18' (or maybe even 20') trailer instead. Still, I have been very happy with my purchase.
Here it is back in August 2015 when I bought my Grand Prix:
The big question is what will you be using to pull it ? Weight will be a huge factor.
When I bought my tow vehicle (the month before I bought my trailer), I went overboard. I skipped half ton chassis vehicles entirely, and instead bought a 2001 Suburban 2500 with the Vortec 8100 V8 engine--that's 496 cubic inches, baby. Chevy rated my Burb to tow 12,000 pounds, and it does so beautifully. I would recommend a heavy duty tow rig to everyone. The
entire vehicle is upgraded over a half ton equivalent; you get stronger axles, a stronger engine, a stronger transmission, better cooling systems, better brakes, beefier suspension, and more. My '98 Jeep Wrangler actually weighs more than my big block GP, but even it fully loaded + the trailer only comes out to 6000 pounds total.
Remember: towing is about much more than just getting a load moving. Safe towing means
controlling your load at all times--on curvy mountain roads, when stopping, etc. Having extra capacity can come in handy all over the place, so choose your hardware wisely.