Yeah, my mate collects emperors children and doesn't play a game without a paragon blade on his
HQ - thanatar tends to go down before getting a hit in himself.
So
HQ choices...
Calleb Decima has to take thallax as compulsory troops, but is an eternal warrior.
Inmar Satarael is an
MC HQ with an invuln save that bounces the shot back on a six.
Archmagos Draycavac is the first dark mechanicum
HQ and can also use the imperial knight household list (Imperial Knights as troops!)
Magos Dominus can join units of
MC's despite the rules
Taghmata magos/archmagos can specialize...
Lachrimallus has no stipulations, but brings back thrall units on a 5+ when destroyed.
Malagra is the
CC specialist, gaining preferred enemy (characters), +1WS and +1 attack in
CC
Archimandrite makes all vehicles gain
IWND
Myrmidax basically turns him into a myrmidon secutor
Ordinator gets a d3 ordinance template once per game and gets armourbane on all his weapons
Makrotek allos an extra fortification and a re-rollable battlesmith 3+
Thallax are really good
IMHO - i enjoy banishing those pesky infiltrating units back to thier deployment zone! (no infiltrators can deploy within 24" of a thallax cohort)