Have not read enough webnovels to have a favorite author and any "least favorite" ... well, I never finished the first chapter of so don't really count.
Favorite authors in print are probably Ramsey Campbell and Robert Bloch, though Douglas Adams and Sir Terry Pratchett also rate way up there. Favorite book - just going from that sample - was Cold Print (the illustrated version) by Campbell - a collection of short stories where only two stories weren't absolutely brilliant, one of THEM was saved by some of the coolest art in the collection.
Least favorite author ... well, for long fiction absolutely, hands down, Henry James (short fiction, though, his "Turn of the Screw" is kind of brilliant) - Portrait of the Lady was 400 pages of nothing - woman makes serious mistakes, winds up in horrible situation, then looks like she's right back where she started and maybe about to make the same mistakes for different reasons all over again. Sheer torture... Though his skill at short fiction almost redeems him, it takes a LOT to make up for that...