As far as I'm concerned (I have my own vampire lore to use if I ever make something featuring them), most vampires would start out evil, as becoming a vampire requires the performance of a demonological ritual of extreme cruelty to the human sacrifice.
However some people might really want vampire powers for a good cause, good enough to justify the ritual, and also somehow have a solid grounding in demonology without being evil or seriously against demonology.
Such vampires may feel obliged to devote free time (which they do have, not needing sleep and being able to switch into human form in order to resist the suns' rays at the cost of many superpowers) to help enough that they compensate for all the killing, or alternatively go vigilante/murderous-vampire-bat-man and try to find villains to suck the blood from.
However most vampires would've been psychos to do the ritual, and become even worse as the ritual demon constantly whispers in their heads like a cross between Robin Williams, Alan Carr, an annoying landlord, a dominatrix and a Spanish inquisitor, who can read the vampires mind, including senses, memories, thoughts and feelings, especially since after death the demon torments them in its' own world for the duration the vampire lived for in the living world.