boat cover suggestions

i am replacing my boat cover with a custom after market cover..my old one was the basic cotton/polyester 11oz grey cover and is falling apart..its my second factory cover in 3 yrs and i want something different this time//

i know Sumbrellas the best but its real expensive so the only other choice is a Sharkskin cover which is in the middle of the three choices..

anybody know if these are better then the cotton factory ones??

any comments on the pros and cons of the sharkskin cover would be appreciated...