I just went through this and the best advice I can give you is to go and look at them (and drive them!) and decide what matters most to you. On the one end is less money together with fewer features, on the other is "fully loaded" and a price tag to match. In theory that higher price tag also comes with higher quality, but I think you'd get a strong debate on both sides of that statement.
For me and my intended use, the Airstream made the most sense. One thing to consider is storage space, which is at a premium on these small rigs (there is no external storage on any of them). If you look at how the Winnie and Coachmen are designed, you will see they build right to the rear of the van. On the Airstream, they leave a good portion of the rear as storage. When you look at them in person, it looks like the Airstream has at least 2x more "trunk" space vs the others. I'm sure it's not quite that much, but it sure looks huge in comparison. You can fit folding bikes back there, camping gear, fishing gear, etc and not run out of space. If that isn't your thing, then maybe it doesn't matter as much, but for us it was a huge factor in the decision. Also, everything on the Airstream was "standard" like the Alcoa aluminum wheels, power window shades, upfit xenon headlights, driver aids like lane keeping assist (for windy conditions), etc. When I compared the price I paid vs what I would get with the other rigs and the cost to upfit them to match the Airstream, it actually came out about the same, so it made my decision pretty easy.
I hope some of that helps.
Best luck in your search.
2017 Airstream Interstate Lounge EXT