I have the truxedo low profile cover and am very pleased. The bracing roll up with the cover. It take me 1-2 minutes to unroll and roll again. No removing the braces and snapping all the snaps. Truxedo uses velcro and a locking mechanism. A great cover.
Locally it ran $500 installed. I picked up a brand new one on ebay for $330 and installed it myself in a 1/2 hour.
I have the Retrax cover, installed it in about an hour (2 people), I think I paid around $850. It locks in any position. It's nice because you can lock it and your tailgate and everything in the bed is secure - it was great for Christmas shopping. I just put pics of it on my gallery today. Let me know what you think.
I have had mine on my F250 for a couple of years and pretty happy. With the weatherstripping, the bed is just about weather proof for gear and stuff. Like above post mentioned, being able to lock it with the tailgate make for a pretty secure storage area.
I have been using the Extang RT (snapless roll up)model for a little over a year now. No Complaints, I like the way it latches from underneath, so you
can lock your tailgate and have at least a little sense of security.