The Cav Version:
Red Fury
Level 3 Upgrade
Infinite Hatred
Dreadknight
Blood Drinker
The Crimson Gem of Lahmia
The Dragonhelm
Talisman of Endurance (or) The Dawnstone
So, either a 1+ rerollable armor save or 1+ armor, 5+ ward. Takes the crimson gem because, if he's in combat with anything remotely normal, he'll probably do at least two wounds to it (usually about 6 or 7 to normal infantry) and be able to immediately heal the wounds back, and because a smaller list (under 3k) with this vamp in it will need all the magic help it can get.
The walking version (for grave guard perhaps, or even ghouls) substitutes Avatar of Death for Dread Knight and takes the Crown of the Damned, since I assume he'll be somewhere near the BSB. 4+ armor 4+ ward isn't quite as durable, but he's still very fast, and if anybody manages to get through his ward save up to twice, he'll restore his wounds in the next combat round. However, he still makes that unit of grave guard nearly impossible to finish all the way off by restoring at least 4 per turn.
An alternative walking build (for large games involving 2+ vamps, where you don't need excess castability) ditches the crimson gem for a 2+ armor save.