1. Ahriman: "If the path to salvation leads me trough the purgatory, then so be it"
2. Honsou: "My plan is to destroy Ultramar"
3. Argel Tal: "We are to bring a truth to the Imperium that will destroy it"

1. Eliphas, the Inheritor
2. Neroth
3. Primarch Fulgrim
4. Magnus the Red
5. Primarch Mortarion

I'd have to go with Ahriman as well, just having finished his book.

1. Erebus - His name is Greek for Chaos, enough said.
2. Ahriman - A man destined to understand Tzeentch, embracing his quest like its a nothing.
3. Kharn - Was so pissed he came back to life, what ever you do don't tell him you parked your RHINO in his parking spot
4. Talos Valrocan - I was so sad he got killed in Void Stalker, I loved his character
5. Lufgt Huron - Gotta love that Power fist of his

1. Abaddon
2. Ahriman
3. Angron
4. Kharn
5. Kranon

Since the OP explicitly said no primarchs:

Zso Sahaal
Talos
Honsou
Sevatar

Onyx (Honsou's bodyguard)

1. Ahriman exile
2. Araghast the pillager
3. Honsou
4. Erebus
5. Zso Sahaal

Ahriman "Necessity is the father of error."

1. Kharn
2. Typhus