Khorne Daemonkin - New Army

[Mr.Gold]

I am thinking of starting an army of Khorne Daemonkin, I currently have Chaos Marines - but no Daemons (except DP). so I was wondering which Daemonic units would be best for me to get next? Bloodletters? Fleshhounds? Bloodcrushers? Soulgrinder? or a Bloodthirster?

[Sly]

Fleshhounds and Soulgrinders.

[Erik Setzer]

Really depends on what you want to do with the army.

Bloodletters are basic infantry Daemons, not very tough but will slice right through Marines in combat.
Flesh Hounds are fast, have some staying power, can do some damage in combat, but might struggle with armor.
Bloodcrushers are tough buggers, fast, they can take some hits and dish out some nice damage in combat. Pair them with a Lord riding a Juggernaut and you have a solid assault unit.
Bloodthirsters are pretty much a requirement if you want to use the book's special "detachment" (you're required to take at least one Bloodthirster or Lord of Skulls). They're quick, can get around terrain, and absolutely tear things up in combat. Don't bother flying with them, you want them to get stuck in ASAP.
Soul Grinders give you some nice ranged fire support, and, most importantly, have the only Skyfire weapon in the army (unless I'm missing missile launchers with flak somewhere, but my book's at home). They can also beat things up in assault, though they're best for going after vehicles and stuff like that, because their weapon is pretty slow. (You can opt for a warpsword as well, but it's still relatively low Initiative, so it would only be useful against something like a Carnifex.)
There's also the Skullcannon, which provides a decent ranged weapon that also strips opponents of their cover bonus in combat, something that could be seriously useful before sending in the Bloodletters or Bloodcrushers.