BakFlip all the way. Ford makes a knock off version that's just as good for a couple hundred less.
They are hard, durable, fold against the cab, sit flush. I've seen dozens of types in person, nothing beats them.
The "cheap" trifolds are usually an all in one system where the folder cover rests on the box and clamps itself to the rails, then unfolds. The good trifolds have separate rails that are clamped to the box prior and then the cover is bolted to those rails.
I can eat more hot wings than you.