Many of the top Soviet aces flew the "Kobruschka (Sweet Little Cobra)", including Grigory Rechkalov, who scored 57 victories, most of them inflicted by the P-39, and the well-known Aleksandr Pokryshin, with 53 victories, again most obtained with the P-39. One Red Air Force pilot, Mikhail Baronov, scored one of his 28 total "kills" by chopping off the tail of a Bf-109 over Stalingrad with the prop of his P-39. Some claim the P-39 was the best-liked of all Western aircraft obtained by the Red Air Force.
Edit: seems Baronov only flew Yaks