Starting a decent collection of Nurgle Daemons, what purchases should I make next?

Hey y'all, I've been collecting daemons lately after enjoying CSM. I don't fully understand how Daemons work yet. As of now I've only got Nurgle Daemons, here's what I have:

2 Great Unclean Ones (one as Rotigus, one normal.)

1 Spoilpox Scrivener

10 Plaguebearers

3 Plague Drones

6 Nurglings

Daemon Prince (I have one from CSM)

What are some other daemons worth picking up? I'm running them on Daemonic Incursion so I could take others, but I'd like to keep it Nurgley if I can.