The only best ones are the few lucky owners that have not had to take theirs back to the dealer for work. The next best are the ones lucky enough to have simple problems that they can fix themselves. The rest are the unlucky ones that have numerous issues and need several trips to the dealer to get them fixed.
For the most part they're all made the same way with the same equipment. You can sort thru the different MFG and find out what they're putting inside them, how they're building them and that's about it.
Airstream is a different breed in it's self. But you pay for it big time. And don't think that because Airstream cost a lot more that it will have fewer problems. They have their own set of problems.
Best thing to do is visit all the different brands of owners forums and read and ask about what model you're interested in.
But be forewarned, those forums are magnets for owners with issues. So it may seem like they all have problems, which they do but it's the types of problems that determine which is best.