I had a roll top on my last pickup and it worked good. Reasons to have one for me was locked, dry, storage of items in the bed and to make the whole bed area look better when not towing. It worked for that. It had a couple of disadvantages also. It's not hard to open, but takes more effort than not having anything. I also learned on winter trips below freezing, never close that thing on camping trips because I had it ice and freeze up on one trip to the point it couldn't be opened. Not good when you need to pack up and pull the trailer home. I also noticed that when I attached the trailer, sometimes the airflow around the nose of the trailer would actually blow (or suck), the lid to the roll-top box open (up), despite there being two latches holding it down. I'd hear a loud bang when the lid would slam into the back window area. I noticed that only happened when I had the cover partially extended to the first lock position. When it was fully open, it held the lid down. Nothing like hearing a loud bang in the truck's rear window when pulling a fifth wheel down the road to wake you up.
On my new truck I have not added one. I've got a spray-in bed liner that looks good all the time, so cosmetically I don't need to cover a scratched bed. Easier bed access all the time. I've also got $1000-$2000 I haven't spent. My son is grown, so I rarely have more than 2 people in the truck. If it's raining I just put items I need to carry in the back seat area.
As others have said, it's all personal needs and opinions (what works best for you).