Very true the Thousand Sons aren't too peachy about being the pawns of Tzeentch either but nonetheless we're still his servants whether by choice or not.
Would totally go Thousand Sons...but....lacking better options....picking black legion Aspiring Sorcerer
Eh, that's a hard one. I'd rather go Death Guard, but barring that... Probably Black Legion. Even though I hate Abbadon, they'd be more accepting of my Nurgle ways.
Night Lords, and then eventually Thousand Son's or a warband from Thousand Sons... As I see it Black Legion- Lead by Failbaddon, the armless HQ choice Word Bearers- Fanatics don't always make the best tactical decisions Iron Warriors- they're too busy sieging fortifications Night Lords- nothing like psychological warfare backed with specific military goals
It's led by Abaddon the Despoiler, there are dozens of minor Chaos Lords like Araghast in the Black Legion. We are after all, talking about an army that is 100,000 men strong.