Allow me to interject my unbiased professional opinion......
I service just about everything out there, and the 'big 3' ....... being Dometic, RVP (Coleman) and Carrier are the industry leaders in roof airs, and I listed them in sales ranking. Dometic is way out there in front, RVP is in the middle and Carrier is a far distant third.
All of these units work well. Your decision should be based on a couple of things, IMHO.......availability of thrained service techs should you have a problem, and how the manufacturers stand behind their warranty.
Dometic has far and away the best tech and service network in the industry. Their warranty is bulletproof and they stand behind it 100% with parts and labor in years 1 & 2 and parts only in year 3.
RVP isn't bad in the warranty area, with a 2 year 100% like Dometic, but no 3rd year IIRC. Their phone techs are knowledgeable and friendly, but they sure do take their time in the re-imbursement department.
Carrier is a totally different animal, from my point of view. Their RV division is just a blip on their corporate radar screen, as they are huge in other A/C areas like home, refrigerated transport, and other big stuff like that. Yes, they make a nice unit, but so do the others. Their warranty department is a real horror show, depending on which phone tech you happen to get when you call. Some know less than nothing! To top that off, the are the slowest payers of warranty re-imbursement in the industry. I had to wait almost 6 months to get paid for a unit replacement....which is totally unacceptable!! Needless to say that I no longer will accept Carrier warranty work.
They also make the tech buy the replacement parts or entire units (been there, done that) and then you have to wait a long time to get paid. The other 2 companies will send out warranty parts no charge from the factory, or a complete new unit if you need one. Then, after filing the warranty claim, they usually get a check to you in 3-4 weeks......totally ACCEPTABLE!
Just though you might find a little 'insider' info useful in your decision.