Honestly, go look for forums for the ones you are interested in and read the comments. People there are blatantly honest about their likes and dislikes, and you can read for yourself what are the good and bad points of each model. Some RVs are based on Ford or Ram chassis, while quite a few are on Mercedes. The diesels seem to get better mileage and are proven engines, but some complain about service availability. You have to deal with DEF on the diesels as well. I’ve had a Class C for the last 6 years, bought before Covid, and love it. If you go used, be wary of models built during Covid as many have complained of poor workmanship by temp workers. RVs are fun, and you kinda take your home with you.