I particularly enjoyed "FDR" by Jean Edward Smith. It is a highly readable biography that looks into Roosevelt's familial and social background, his political career, and dives deep into the political and social psyche of all the eras Roosevelt lived in. It is a highly rated biography that takes a hard but fair look at Franklin Delano Roosevelt from all angles, both giving credit where credit is due as well as diligently marking cynicism and opportunism wherever it is present.

Jean Edward Smith is a highly decorated biographer and political scientist who has taught at Marshall University, the University of Toronto, and Ashland University (among various other visiting professorships). While his biographies are not targeted at a strictly academic audience, they are extensively footnoted and offer countless ledges for deeper dives.