I'll second the recommendation of Neil Gaiman - American Gods is superb, as are his other books. His style is dry and dark, but there is a lot of warmth there too. He is also not afraid to take his characters to the limit (eg: he's not afraid to kill off a good character - like Iain M Banks).
A new author I've discovered is a Scottish writer named Hal Duncan - his work is challenging but definitely worth it.
I prefer sci-fi and what I would call cyberpunk (eg: William Gibson) to true fantasy, but I think these two authors are in a 'crossover' range.
