Fighters?
Still need more Japanese and Soviet stuff. The Ki-84-Ia closed off the largest gap in the entire plane set, but there are still much more smaller holes.
The Japanese fought four years against the USN and both the Army and the Navy produced variety of aircraft to try and counter the USN - of them only two Zero variants and the N1K2 has been modelled. Only a single Army fighter of Ki-61 is in the set. A grand total of four fighter planes in the entire Imperial Japanese set. With the Ki-84 that's still only five.
A6M3, Ki-43, Ki-44, Ki-45, and Ki-100 are all likely candidates for the (more or less) completion of the plane set.
The VVS has it even worse. These guys fought the LW for three years in the largest air and ground battles of WW2, and for every LW variant in the air they tried to match it with their own . Of all those planes we only have four, concentrated on the mid/late war.
I-16, Mig-3, LaGG-3, P-39N, P-39Q, La-5, Yak-1, Yak-7B, Yak-1B, Yak-9M, Yak-3 are all likely candidates.
To choose two of them for the next next update, I'd go for the Ki-44 and the P-39N.
The Ki-44 adds a midwar alternative for the Imperial Japanese, and the P-39N fills dual purposes in providing the one of the most important fighters of the VVS struggle, as well as adding in a Pacific plane for the USN to use.
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As for filling gaps for already existing plane variants, the P-38G is probably the most needed. The RAF needs a better Spitfire9, at least upto '43 standards, and the LW needs a gap-filler between the G-6 and the G-10 - the Bf109G-14 which would become one of the most numerously produced G models in the 109 family.
