I’ve read more books by Michael Moorcock than any other writer*, some sixty volumes, at least one of which was an omnibus, and I have the Pyat books in a box somewhere waiting for a rainy fortnight.
In no particular order, other than the alphabetical, here are my twelve favourites:-
Behold the Man
The Black Corridor
The Brothel in Rosenstrasse
The Condition of Muzak
A Cure for Cancer
The English Assassin
The Final Programme
Gloriana
The Ice Schooner
The Land Leviathan
Stormbringer
Warlord of the Air
Of course it’s all subjective and on another day different titles would have made the list. I note that all four of the original Jerry Cornelius titles got chosen, as did the first two Oswald Bastable books. There were some superb books published under the Eternal Champion umbrella (for purposes of this list I’m regarding only those obviously set in a fantasy world as part of the cycle), but in my mind they’ve all pretty much merged into one huge saga. I’ve picked only Stormbringer for the list, which was the very first Moorcock book I read and introduced me to the character of Elric, the albino prince of Melnibone, and his soul drinking sword.
*Most of the Moorcock titles were very short, so in terms of word length I suspect the gold medal goes to Stephen King, and by that criteria several other writers are almost certainly ahead of Moorcock.