My two favorites are the following; luckily someone has already explained the von Carsteins & the Lahmian. The last is the Blood Knight line, which I will leave to a player who enjoys them to describe.
Strigoi are the lepers of the vampire world. Cast out and hunted for their arrogance, they live like beasts, feeding off of the recently dead & buried. Called "the Ghoul Kings" due to the flocking of the flesh-eaters to their presence, they look upon the other bloodlines with hatred & disdain, blaming them for all that they have lost & all they currently suffer & endure. When the courts of the ghoul kings march, it is with baleful howls & lust-filled hoots. Waves of ghouls, dire wolves, fell bats and all other bestial creatures surge forth from their hiding places. The brute force of death is brought to bear, and woe be to they who stand in it's path.
The Necrarchs are isolationalists. Locked away in hidden mausoleums & forgotten towers, they strive to further their mastery over the dark arts. So complete is their grasp upon necromancy & vampiric lore that they rarely feed, spending vast stretches of time locked away in secret. Seldom seen, they have passed mostly into myth. When they do come forth and wage war, it is usually over some great magical artifact or treasure trove of arcane knowledge. Their might is so incredible that once such a campaign is complete, there is usually nothing left to remember it, and so the vampire retreats to his solitude, to further study his new conquests.
Brahm