Really depends on what your goals are. I've always preferred the simple, soft, roll up covers as my primary objective is only to have the ability to keep cargo somewhat dry.
If we you want the ability to lock and secure the bed, a hard cover may be better.
I got the Ford retractable cover with my order. Retrax with rail slots for mounting racks.
I cant tell you how much I love this thing. 3k miles +-
Multiple trips to Lowes Home Depot, etc.
Open or closed, stays secure no rattles,
Open still fits my karts in it. 6.5 foot bed, Super cab
Fully packed and closed trip to desert in up to 108 degrees. Kept all the gear, kids luggage, coolers safe, secure, and cool !!
Did great on 25 miles of beginner to intermediate off road trails too.
105-107 mph no worries. (allegedly)
Freakin awesome.