Personally, rather than specific characters, I'd actually like to see more, decently written, IG novels. The majority of what's been put out there so far has been shit IMO. Maybe get some of the better BL authors to have a go at doing some novels focusing on some of the elite Guard regiments. Like if they had someone like ADB, Wraight or Abnett to do, for example, a Harakoni Warhawks novel, I'd literally be throwing money at BL.
And if they use Orks as villains, get the damn fluff right. If I read one more instance where some random guardsman kills an Ork with a combat knife, by slitting its throat, I'm gonna smack someone with a keyboard.
The human appendix. Proof of a higher power. A divine kill switch so to speak.
No one really likes a smartass, but people tend to like a dumbass even less.