I recommend....
The Horus Heresy series (with the exception of "Descent of Angels", THE weakest novel in the whole series so far and the only Warhammer 40k book that made me say "meh")
Both the Eisenhorn and Ravenor Series (Excellent novels about kickass Inquisitors and read them in THAT order too...Esienhorn series first then Ravenor)
I liked both Space Wolves Omnibuses, I thought they were interesting and fun to read
I also recommend the Wordbearers Trilogy as well...very cool to read a series from a The Chaos Marines point of view (I got a kick out of the fact that two of the main characters of this trilogy are mentioned in one of the short stories in the "Heresies" Novel set during the Horus Heresy/Great Crusade before the Chapter was subsumed by chaos)
The Horus Heresy series (with the exception of "Descent of Angels", THE weakest novel in the whole series so far and the only Warhammer 40k book that made me say "meh")
Both the Eisenhorn and Ravenor Series (Excellent novels about kickass Inquisitors and read them in THAT order too...Esienhorn series first then Ravenor)
I liked both Space Wolves Omnibuses, I thought they were interesting and fun to read
I also recommend the Wordbearers Trilogy as well...very cool to read a series from a The Chaos Marines point of view (I got a kick out of the fact that two of the main characters of this trilogy are mentioned in one of the short stories in the "Heresies" Novel set during the Horus Heresy/Great Crusade before the Chapter was subsumed by chaos)