Yak1/Yak7 variants(Yak 1 b would be sufficient IMO)
La5/La5F/Lagg3 (one of them at least)
Yak-1B (with M-105PF) does not cover the 1941 gap and is similar by performance to Yak-7B which is similar to Yak-9 which is similar to Yak-9T already modelled in AH except 37mm cannon. So it would be better to save time and money and just convert Yak-9T into "hybrid" version with different load outs. (20mm - Yak-9, additional fuel tanks - Yak-9D, 37mm - Yak-9T, etc)
To cover 1941 ("Barbarossa") gap the earliest version of Yak-1 must be modelled as well as MiG-3.
As for LaGG-3 it would be better to model "hybrid" version of LaGG-3 (M-105) which will represent all weapons modifications of late 1941 and early-mid 1942 (12,7mm , 20mm, 23mm and 37 mm). It will cover late 1941-early 1942 gap.
To cover mid-late 1942 gap La-5 (earliest version) must be modelled. It would be good to have Yak-7B as well but it can be substituted with Yak-9 20mm.
To sum up the results: Yak-1 (earliest), MiG-3, LaGG-3 (hybrid), La-5 earliest + Yak-9T converted into hybrid (Yak-9 with different load outs)
Pe2 (almost essential)
Yes, Pe-2 is a must. It's not quite clear which version though. Probably hybrid of 1941-42 to make it usefull for as many as possible special events.