If the conversation is expanded to include variants beyond those planes which have recieved AH2 standard models, I would most like to see the Yak-9UT. This is soley for personal reasons, and has absolutely nothing to do with what the planeset needs, or what ToD needs, or even Special Events (which is funny coming from me, as I'm usually approaching it from that angle).
Using Tony William's gun effectiveness article, the Yak-9UT should have over twice the weight of fire as the Yak-9U that we have. As this is the most glaring weakness of the Yak-9U (in my opinion) I think that the addition of this monster would prove rather popular in the MA. Depending on what performance loss there may be, this would give the Yak greater firepower than the La-7, which may make it a more attractive option to some. Granted the La-7 with WEP still owns the Yak, but at least one thing would close up the gap.
I would really love to try out the combo of 1xNS-37 and 2xB20 cannons. It's just scary how fun that would be.
-Sik