There are too many to make a full poll for this, but who is your favourite GW author? (Black Library books is what I'm thinking about, plus the GW Novels from before the days of Black Library).
Jack Yeovil (author of the Genevieve the Vampire books and several Dark Future novels, for those who remember the old stuff) has to be my favourite, although Brian Craig (the Orfeo trillogy and Pawns of Chaos that I've read) is also very good, as is Ian Watson (I'm reading his 1990 novel "Inquisitor" at the moment)
Authors I don't like are Robin D Laws (author of Liar's Peak most recently - the Angelika Fleischer novels). They're still good novels, but I find his style of writing too slow and ponderous - he describes every little thing in excessive detail instead of getting on with the plot.
So who are other people's favourite and disliked authors? or who hasn't even ready any GW fiction?
[update] I've just been in to town to the Games Workshop store and noticed another author who is very good (again, Warhammer) - Bill King, author of the Gotrek books. I've read one book of his (Giantslayer) and it was very well written