The RetraxPro is a good cover. But, you should also look at TruckCoversUSA. Like the RetraxPro, TCUSA is also made of double-walled black powdercoated aluminum. TCUSA has a textured finish which is less likely to show scratches than the RetraxPro's smooth finish.
Other differences, I'm not saying the differences are bad or good, they're just differences:
1. TCUSA is spring loaded and locks every 12 inches. RP is not spring loaded, you can position the cover anywhere and lock it into place.
2. TCUSA requires 4 drain tubes, two in the front and two at the rear. RP requires two in the front.
3. RP is easier to install than TCUSA.
4. TCUSA slats are interconnected. The slats in the RetraxPro are connected with rubber.
Pace Edward covers are OK, but I would put them a notch below RetraxPro and TCUSA. The PE Full Metal Jack Rabbit is much nicer looking than the PE Jack Rabbit (vinyl laminated aluminum). Again, PE covers are not bad covers, you probably would be happy with one of these also.
I don't like the Rollbak...at all. I don't like that the cover has a tailgate bulb that just sits against the inside wall of the tailgate.
RetraxPro
TCUSA
Cross sections; RetraxPro on the left, TCUSA on the right. If you're wondering how water does not penetrate throught TCUSA, the answer is that there is a seal underneath the slats that takes water to the side rails. The rails have water channels that then take the water out either through the front or rear drain tubes. It sounds weird, but it works, and works well.