My want list for WWI (in addition to likely official version units):
2 types of infantry per Empire: basic (cloth caps, early war) & armoured (steel helmets, late war). Which type I need depends on which are provided in A&A1914, probably a mix.
At a pinch, late war types could be in 3 sculpts: Adrian helmets (F, I & R); Brodie (US & UK) & Stahlhelm (CP)
Cavalry
Armoured trains (a single generic type would do; would work for WWII also)
Observation balloons (generic)
Bombers
Airships
3 types of fighter plane for each side representing advancing technology
reconnaissance plane (2 seater)
Destroyers
MTBs
Aircraft carrier (HMS Furious)