The roof should not be much of a factor in determining what camper to purchase. There are more important considerations. I have had two campers with metal roofs and one with rubber. Both have their advantages and disadvantages. Metal roofs tend to expand and contract with the temps so recaulking is important. I could never keep them painted for more than a year or two, perhaps because they sit in the snow in the winter. Finally, on one camper I used 1/8 inch think sealant that was more like a bed liner than a surface coat for a roof. But, it fixed the roof paint chore every couple years. Rubber roofs more easily puncture when hit by branches. Most punctures are easy and inexpensive to fix, however. If you are not carrying anything on the roof, I like the rubber.
Hope you enjoy the camper, they are nice.
2005 Dodge, Cummins 4x4 quad cab, auto, white, dually 3500. 2009 Pacific Coachworks Tango 299bhs.