Brand names basically mean nothing. A few giant corporations own most brands and make them basically all the same. Do a very very thorough walkthrough and do not accept a camper new if it still needs really obvious corrections. The boutique brands like Oliver or something similar may have better quality control but you will certainly pay for it for what you get. I would also do business with a dealer who is privately owned, has a good reputation, and also has a good repair team in house.
My wife and I are considering getting one of those converted camper vans based on Ram, Ford, or Mercedes cargo van chassis. We could go for new or used, and budget is not a major consideration.
Alternatively, maybe we could do the conversion ourselves. I've seen van build kits that allow you to do everything yourself. What are your thoughts on DIY vs. pay for someone to upfit?