If you don't mind spending more, the Alumaguard is sure nice.
Otherwise, I installed the cheapest Carefree many years ago and it worked great right up till I traded the last TT in.
Some will disparage toppers but they work great for us. Keeps tree junk off s/o roof and keeps the heat down on the roof of the s/o - which is considerable.
One tip I have is to try and give it an extra turn when installing. I did so and never had a billowing or puddling issue with mine.
Also, try to mount it with the most slope possible. Water sheds off it better.