Even in the new season, the primary contribution of vampire lords still seems to be their command ability, and as per 3e core rules you can't use the same command ability more than once in the same phase, even if a different unit is issuing and receiving the ability. So after the first vampire lord, you're paying a fair chunk of points for an ok-but-not-stellar combat statline and a single cast/unbind wizard with no signature spell and a pretty bad spell lore, and the points just don't add up.
IF you want to try anyway, though, then you definitely want to be running vyrkos or LoBlood. Vyrkos vamps get an extra buff aura and casting rerolls, which makes having more of them to spread that aura and reliably throw out some endless spells more attractive, while LoBlood get to choose between an extra +2 attacks, at which point they almost start to feel threatening... almost, or +2 to cast, which again helps reliably cast mystic shield and endless spells.
What vamps really need to shine, though, is simply to be more modular. Make the command ability an option, not default, and have it come with a pile of alternative options including various command abilities, offensive buffs, defensive buffs, and spells. That way different vampire lords can bring different benefits to the table and not overlap so much. The obvious way to do this is with bloodline traits as 'unique enhancements' where each dynasty has a set of 6. Then either fix the vampire spell lore to be good, or else drop it entirely, have vampires and necromancers share the same 'necromancy' spell lore (maybe with different bonus effects on 9+ casting to set them apart), and include a couple unique signature spells for each dynasty in their bloodline trait enhancement options.
