Have used Diamondback covers on our last two trucks, so close to ten years of use. Pro's are excellent build quality, very good weather sealing, lash points on the top (and you can add more) with a very hefty weight rating. Front and rear sections are easily removed. Locks do not depend on a cable, so they cannot be unlocked with a coat hanger. Subjective pro is IMO they look good.
In the past nearly ten years, nothing has ever needed to be repaired or replaced on either of our covers. I would imagine that the weather sealing tape might need to be replaced on day, but that has yet to happen.
The only con is that in order to remove the entire top, you have to un-bolt four clamps. So you have to budget about ten minutes or thereabouts to do full removal. The four support struts just pop off.
If you live in a very sunny place, consider the bright aluminum covers. Yes, they do get hot when sitting in the sun all day long, but they still are not as hot as the black ones. Of course, a lot of the color decision will be dependent on the vehicle's color.
IIRC, DB has a military discount, if that is significant to you.
Cannot speak to Paragon covers.
hth,
C