Who wins?
History of Middle-earth vs The Silmarillion
The Silmarillion wins 91% to 9%. 8 more put them in the same row. From Lord of the Rings Novels Tier List. Pick a side.
gooseguy94 on History of Middle-earth: 12 volumes of drafts, for the truly committed
goosefan6558 on The Silmarillion: Beren and Luthien and the fall of Gondolin, the real lore
Lord of the Rings Novels Tier List: the full ranking