They're both quite strong. Both give several bonuses to augument martial capability, both have means to raise armies of minions, both are very hard to kill. I would say that a gravelord works better as maurading warlord type while the vampire works better as an evil overlord type.
Except a vampire requires rest, a graveknight does not.
Graveknight can operate in daylight?
Graveknight can operate in daylight?
Nothing says they can't.
Then I'd go graveknight.
Graveknight anti-paladins are pretty sick, dunno about vampire APs.
They both can come back if you don't know how to kill them.
They can both make more enemies and control them.
I think though, one on one I'd rather fight a vamp than a graveknight.
Graveknights bring alot of offense to the table.
Does the creature you add the template too have to not already be undead? Make a Vampire Graveknight AP!
I would think it would depend upon the capabilities of the individual or group opposing them.