The Armies of Daylight
I stuck with Barbara Hambly's Darwath trilogy out of love for the author, only to find an ending that made three books of struggle feel pointless. Flat protagonists, frustrating plotting, and one of the most unsatisfying finales I've ever read.
King's Dragon
An intricately constructed medieval fantasy with a promising prologue, but its painstaking worldbuilding and a young woman's brutal loss of agency couldn't sustain my interest. After two attempts, I still couldn't finish it.
The Many-Colored Land
A one-way ticket six million years into Earth's past, a cast of misfits, and the delicious terror of the unknown. A sprawling science-fantasy epic that initially blew me away.