I think the 13.5 unit is the most bang-for-the-buck. Brand is immaterial, they are all good products. Dometic has a 3 year warranty, can't speak about the others.
2000 Winnebago Ultimate Freedom USQ40JD,
ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG 11B5MX,Infantry retired;Good Sam Life member,FMCA." My fellow Americans, ask not what your country can do for you, ask what you can do for your country. John F. Kennedy