Being a fan of the not so common stuff, I'd like to see things that haven't been kitted yet, or only seldomly.
For a military helicopter, the top of my wish list is a 1/48 Atlas Rooivalk.
In the way of civil whirlies: a new tooling in 1/48 of a bell 222 so we fans of it never have to suffer the deplorable old AMT kit again.