From my mental to-do list, top 5 in two categories.
Real history:
1. 2nd China-Japan war, in particular before the Flying Tigers.
https://en.wikipedia.org/wiki/Aerial_engagements_of_the_Second_Sino-Japanese_War2. Battle of Shumshu (Kuril Isl.) It was 1945 but there were SB-2, Ki-43 and MBR-2.
3. Soviet landing in Chongjin (Seishin), 1945.
4. Black Sea and Sevastopol in 1942. Many missions were made in 20+ years, but most of them were far from the historical events.
5. Operations Carmen and Carmen II - 1943, Kursk rail hub and the Soviet industrial sites.
Alternate history:
1. Allied bombing of Baku in 1940.
2. Operation Eisenhammer in 1944 or 1945.
3. Turkish Straits crisis unresolved and the Soviet landing in the Straits, 1946 or 1947.
4. Romania rejects the Soviet ultimatum in 1940. Action in Bessarabia and over Bosporus (according to the Soviet plan in real history, Black Sea Navy was supposed to block the Straits if Romania decides to fight).
5. Catalina affair aftermath - Swedish Tunnans protect the S&R operation and engage Soviet MiG-15s, 1952.