Atticus: you'll never get MS to give you such specific options.
I would, however, wish for the ability to have some freedom in the creation process. Stock aircraft are a shadow of what is available in terms of how the sim is constructed. So to that end:
2 or 3 very light aircraft, like gliders and the like.
4 or 5 GA aircraft that are prolific.
6 or 7 airliners (Airbus, Boeing)
1 or 2 specialized aircraft, like the Moller Skycar or Osprey.
2-5 military aircraft from around the world.
The mil aircraft could be anything from C-130s to AN-225s. The actual type is not important, just so long as the technology to implement them is there.
The real test is that there is a way to create any aircraft that currently or potentially might exist in the next few years. If they don't include it in the initial release, it will certainly be created within 6 months of the sim being sent out.
Given that this a new sim, it should be maintained that the modeling process (and program used to create it) will most likely be new or very recent, and therefore very hard to get or obtain. I don't expect any freebies on the modeling side, since MS has shown itself to be an uncompromising b***ch in this respect from the past.