What are you towing it with? Bigger is better, but if you're towing with a 1997 2 door Tahoe with 200,000 miles on the original 350, smaller is the only option.
I'm personally not a fan of enclosed trailers, but I do see the benefits of them also. They get stolen more, you need more truck to tow it with, they get you less gas mileage, and an open trailer gets your car looked at and your sponsors recognized 1000 times each time you go to the track. I can't remember the last time I stopped to fuel up on the way to the track and didn't spend 20 minutes talking racing with people that come over to look at the car. Rain sucks though
Just my 2 cents