Rough Country makes a pretty good trifold. It is ready to pick though. Just need to slide a hook between the top of the tailgate and under the tonneau, twist, grab, and pull. It's that easy to get into. It is pretty good at keeping water out though.
I have a Retrax also. I got the poly cover, but wish I got the aluminum one. The version with the T-slot rails can be used for a variety of attachments. I got a set of tie-downs from etrailer.com for fairly inexpensive that allows me to secure tall loads of I'm unable to close the tonneau, or if I have to set it on top of the tonneau. Retrax has a motorized version that'll help prevent theft. The non-motorized version needing a key helps as a theft deterrent, but you can't lose the key, can't forget to lock it, and it's avidly fairly easy to pick if somebody is determined enough. Once the lock is open there's nothing preventing the tonneau from opening all the way. The more features you want with a Retrax the more expensive they become.
As somebody already pointed out, it just depends on what features you want versus what sacrifices you're willing to make. Most tonneau covers do a good job keeping water out. Perhaps selling on a price point would be a good start.
diamondbackcovers.com
