spoiler contained for ravenor rogue and eisenhorn in black in the middle ish bit so dont highlight if you havent read it.
eisenhorn is my favourite BL series becuase of its characters. i agree with autolocus (sp? i dont want to scroll up

) ravenor is an awesome series but i think it focuses too much on the pursuit of an individual without focusing as much on specific characters. we recieve very little about any of the characters but plenty about the S**T they find themselves in. eisenhorn however is aweomse because the main characters DO die unlike most other books.
ill admit that thonius the unlikely one the interrogator, the supposedly devout and pious one considering his status, i the one that gets possessed and attempts a rampage but in the end he saves the day.. however in eisenhorn ALL eisenhorns principal agents are wiped out or leave in the end, judge dredd, oops i mean fischig, is turned in to a daemonhost, bequin is in stasis/dead to all purposes, aemos is well it says he speaks his last owrds so insane/dead/whatever, nayl leaves kara laeves, voke dies, maxilla is killed, heldane attempts murder, this is all off the top of my head don't remember much more. it's the truest to life. vibben. she dies as well and midas. its the fact that eisenhorn starts the third book with 50 ish primary agents and the distaff and works out with eisenhorn having pretty much a daemon as a buddy at the end. its true to life. a psyker and a ganger walk in to a processional ( a chicken crosses the road in 40k...........) and kill lots of cultists using psychic powers, stubbers, swsords, cover and brains, compared to guns and possession. and a xenos tech worm thing. its true to life ish...
hope i havent wasted too many peoples time with my mad ravings.....