yes, this could go on forever.
In my opinion, the best out there are going to the most expensive. If you are talking about value, that's a whole different game. The Futaba MZA 18 channel is probably impossible to beat but it's 3000 dollars. You can get the spektrum DX18 for 800. It's the cream of the spektrum crop. Probably the best value is the Futaba 8FG super because it can be expanded to 14 channels. The DX8 is right up there for value as well.
I really haven't seen any new stuff from airtronics. I ran airtronics radios years ago when I raced cars, but no one I know uses them for air. The JR radios are top notch as well and the 11x is my favorite from them because it's 11 channels, dsmx, and only 750 bucks.
The turnigy 9x is a super popular radio because it's 9 channels for under a hundred bucks.
So........what's the best radio? Probably the one you can afford and the one that has the best local support, which usually means whatever the people you fly with fly because then you can get the most help with it.
As far as "it must be able to do......." any of the high end radios can do about anything.
I will mention though that futaba still sells heli versions of their high end radios and heli versions where the JR and Spektrum radios have all the programming in each. I think that the Futaba radios also have the same programming, it's more about which features are highlighted and optimized in the radio.
As far as building a plane around a radio, you obviously have limitations on your programming and number of channels, but you have options there with things like a smart fly system, Futaba and Spektrum have Sbuss type systems, you can link servos with y harnesses like the old days etc, so it comes down to what are you wanting to do. If I had an idea of what you are trying to build and fly, I could make some recommendations.
I personally own a DX8 because I wanted to have the options to expand later. I use all 8 channels on my cub because of the configuration I chose, but I could have done it with 6. The mixing options I chose required 8. If I were to build a large plane that required a lot of servos working in tandem, I can expand through the aforementioned smart fly systems and others as much as needed.