Mike - I went through this last year.

One piece covers - can color match, secure, best at keeping the weather out. Hard to remove and hang on if a strong wind is blowing the wrong direction
Roll up covers - secure, opens up most of the bed for tall things. Lots of moving parts that might get finicky over time, not as weather tight
Tri/multi fold - secure, opens up 2/3 of the bed for large loads, some models are easily removed for full bed use. Not as weather tight

I chose a tri-fold that comes off easily. A close second was a 4-fold that folded up exposing over 80% of the bed but hard to remove.

The one piece in matching color is hard to beat for best looks