Possible contenders:
Andrei Zhdanov: He was one of the key players in the siege of Leningrad, and from 1946 until his death in 1948 he was seen as Stalin's most likely successor. Of course, in 1944 he wasn't Stalin's chosen successor, but just one of the big players. He was also a pretty severe alcoholic, so even if he takes power he would be gone in a few years.
Vyacheslav Molotov: During the war Molotov was Stalin's right-hand man (although his stature declined in the post-war period). Certainly as the second most powerful man in the Soviet Union he would play a huge role in any subsequent government.
Georgy Malenkov: During the war Malenkov was one of the five most powerful men in the USSR as a member of the State Defense Committee. Malenkov had some reformist tendencies during his duumvirate IOTL, such as advocating for a greater focus on consumer goods and being anti-nuclear weapons, so he'd probably follow that path ITTL.
Beria was universally hated by everyone, and would almost certainly be liquidated shortly after Stalin's death (or the end of the war if he's deemed too useful during wartime). Zhukov won't take power because one of the Party's top fears was Bonapartism (a situation where a military officer takes command and undoes the Revolution). The most likely form of government is collective leadership with one person as first among equals.
Andrei Zhdanov: He was one of the key players in the siege of Leningrad, and from 1946 until his death in 1948 he was seen as Stalin's most likely successor. Of course, in 1944 he wasn't Stalin's chosen successor, but just one of the big players. He was also a pretty severe alcoholic, so even if he takes power he would be gone in a few years.
Vyacheslav Molotov: During the war Molotov was Stalin's right-hand man (although his stature declined in the post-war period). Certainly as the second most powerful man in the Soviet Union he would play a huge role in any subsequent government.
Georgy Malenkov: During the war Malenkov was one of the five most powerful men in the USSR as a member of the State Defense Committee. Malenkov had some reformist tendencies during his duumvirate IOTL, such as advocating for a greater focus on consumer goods and being anti-nuclear weapons, so he'd probably follow that path ITTL.
Beria was universally hated by everyone, and would almost certainly be liquidated shortly after Stalin's death (or the end of the war if he's deemed too useful during wartime). Zhukov won't take power because one of the Party's top fears was Bonapartism (a situation where a military officer takes command and undoes the Revolution). The most likely form of government is collective leadership with one person as first among equals.