Depends what you are going to do with it. If you are going to use it only occasionally, the 7000 lb axles are enough. If you plan on using it more than a few times a year, go with the 10,000 lb axles. I ordered mine with the 7000 lb since i only use it 3-5 times a year, and only load it with a car. ( no golf cart, tool boxes, extra parts, etc) I got the drivers side jump door on mine, well worth the extra $300 as you can get out of the car without having to climb out the window. I had a winch plate installed in mine, then bought a wireless remote control 3500 lb Warn winch and installed it myself. Pulls the car up with no trouble, but again, if i was using the winch on a regular basis, I'd go to a bigger winch. If you are going racin, then you ought to consider a generator package also. If you are in PA, both axles have to have brakes, some states only require one axle brakes. It will need to be inspected once a year also.
I tow using a class 3 reciever, with drop hitch, equalizer bars and a sway control. Dont skimp on the tow setup, no need to try and save a few hundred bucks and lose the trailer and car to an accident. I have a 2000 CTD 2500 fora tow truck, love the diesel, and gets very good mileage towing. I have over 5000 miles on my trailer, I'm pretty happy with it. ( a Haulmark economy, cost me $5300 picked up at the factory by me in 2005)