Here are some further reading suggestions, covering a range of interpretations:
Robert Tucker, Stalin in Power (1990)
Isaac Deutscher, Stalin: A Political Biography (1949)
O Figes, The Whisperers: Private Life in Stalin’s Russia (2007)
S S Montefiore Stalin, The Court of the Red Tsar (2003)
Sheila Fitzpatrick, Stalin’s Peasants (1994)
Sheila Fitzpatrick, Education and Social Mobility in the Soviet Union 1921-1934 (1979)
D. Filtzer, Soviet Workers and Stalinist Industrialization (1986)
Stephen Kotkin, Magnetic Mountain (1995)
You can also read our blog posts offering a range of perspectives on Stalin, here and here.