I ALSO went crazy for weeks comparing them all....and finally went with the LoMax Tri-Fold (its like the Bak-Flip but more low profile).You can hardly tell its on and is only like 1/4" above the sides.
My 1st choice was the Diamondback as SVTFORDRAPTOR mentioned above,BUT,just didnt want the high profile and it sitting above the bed rails....The LoMax is actually what WeatherTech sells...its just rebranded with $$ added to it...Personally I've seen the "roll-up" covers in action,and just dont like,and IMHO would think they would freeze up a little and become stiff....So,maybe I confused you more....but bottom line,what I learned is there is NO right answer,its what fits your app...and how deep your pockets are...
My GF wanted me to get a motorized one..HAHA...like the Raptor doesnt have enough "tech" things that can go wrong...no need for ANOTHER problem if motor fails....
I LOVE the LoMAX..it took about 30 minutes to install,and so far has been 95% dry inside...just a few drops near back bed cornors,sometimes....yesterday it POURED...and was dry...so must be angle of rain I'd guess.....
I also got a KILLER deal on it,and if you PM me,I'll send you the info......and no,I'm not a Bed-Cover Salesman...LOL...