Now it may be me because I am making a Word Bearers army but I am going to plug the Trilogy.
All written by Anthony Reynolds
Dark Apostle
Dark Disciple
Dark Creed <--about 2/3 finished
I started reading them about a year or so ago and they rate on my scale about a 8/10 for storyline, action and good all around Chaos death and destruction.
Now this is the first time I have made a post about a book, but last night there was a detail segment of about 30 pages in "Dark Creed" of the Word Bearers boarding a Battle Barge of the White Consul Space Marines. The depth of the writing of them pushing their way towards the bridge of the ship was pretty intense. I wont go into any more detail about what happens later but suffice to say I read 180 pages strait with out even looking up the book was that captivating.
It is out of the norm that I get that involved in a book. So, if you are looking for a good series of books to read pick them up or I am sure soon to come will be a Omnibus (not sure how long since Dark Creed was just released a few months ago)
This pretty much says it all !!!