Most suitable brand for the roughest roads?

I like the one in my signature, and I bought it for just the purpose you describe (and more).

2006 Outfitter Apex 8. Aluminum frame, modest (but not minimum) weight, 44 gallon fresh water, casette toilet, 540 AH battery capacity, all the comforts of home almost, but able to handle some pretty extreme off-road travel and camping. (with a capable truck)

See my trips here if interested.
Also see Whazoo's trips in a similar camper for really extreme off road.

I would say smaller and lighter with minimal options. We do primarily forest road boondocks and your truck is going to be put to the test so consider that stress on your rig. Probably don't really need
AC or a generator if you are planning to go into the boondocks. We go 3 days easily with just one battery, 30 gallons of water and 12 gallon black and grey tanks for 2 people. I do carry extra water and we use the outdoor shower.

The more features you have the more that can go wrong. Still, it depends if you will slow down and have good shocks or not. I've taken mine over a lot of gravel roads and mountain fire roads without an issue over 10 years. Other people haven't been as lucky. I do slow down when I see the bigger bumps.

I can't say I'd pick one brand over another for just traveling rougher roads. There are advantages and disadvantages of each construction method. Slides are more complicated, but I wouldn't give up my slides.