Marks71 -
As someone who has looked at Roadtrek, Airstream and ARV fairly extensively, driven two of the three and spent some time in each, I'll give you my general thoughts, for what they are worth. I'm still dithering on what direction I'm going to go and don't yet own any of them, so I have no owner-allegiance. I think all three are very nice vehicles.
I've discussed my thoughts on ARV vs. Roadtrek in a previous post on this thread, so I won't repeat them here.
I initially looked at the Airstream Grand Tour. The biggest shortcoming of the AI, for my intended use, is the more traditional systems found in the AI. AI isn't available with an all electric/diesel set-up. It uses propane for the generator, heat and cooktop. It doesn't have the underhood engine generator or a diesel heater, nor does it have the option of large lithium battery banks. Those are expensive components, which would drive the price of an ARV significantly higher than the AI. I would guess that the systems and some of the other ARV special features probably account for about half of the price differential between ARV and AI. If those features aren't important for your use, then an AI may be a better value.
The price differential between a Roadtrek with the features described above and an AI is much less than the ARV, of course, but the Roadtrek interior finishes, while nice, are not equivalent (in my opinion) to either the AI or the ARV. And Roadtrek does not offer air suspension and a few other upgrades.
AI and ARV both have very nice interior finishes. As to which is more appealing, that's a matter of personal preference, as you noted.
I'd say that ARV combines the higher finish levels of AI with the more advanced systems available (as options) from Roadtrek. If you want both, ARV is the only manufacturer I've identified that can provide both.
As far as I can divine, the balance of the price differential can be attributed to ARV's customization of each vehicle. ARV allows a buyer to pick and choose chassis options and color, and all of the interior finish materials. ARV also allows extensive customization of the layout, cabinetry, accessories, lighting and just about everything else. All those custom design features are nice, but they come at a substantial cost, because building one-off vehicles takes a lot of design and administrative time and effort. ARV does not benefit from the economies of mass (relatively speaking, of course) production and assembly line manufacturing that AI and Roadtrek can achieve.
If the ability to engage in a custom design process isn't important for your use and desires, and you don't want both a higher finish level and the more advanced systems, then an AI or Roadtrek may be the better value. In that case, the choice between AI and Roadtrek would depend on whether AI's finishes or Roadtrek's systems are most important to you.
As I said before, I think they are all very nice products that would hold different appeal to different buyers based on their intended use, as evidenced by the loyal following each brand enjoys with its owners.
I have no dog in this fight, but perhaps you'll find my observations useful.