I prefer the ones that look human, but have the ability to transform into their second "demon bat" form. Or even demon-esque form(like Olrox). I generally like them to remain in their human form as long as possible, and only transform to tap into that extra power(like Frieza in DBZ). Never transform to prey on humans. It's always a failsafe after their human form is defeated. I didn't care for Brauner and Olrox in LoS, because they were already in bat form(as were the lesser vampire enemies).
Of course, as vampires were concerned, I always loved the idea that they were the nobility of the monster world. That you rarely seen them as normal enemies in the classic timeline(other than the ones in CV64/LoD and the Draculinas in OoE) and most of the time, they are so powerful, they are bosses. It makes them seem "special".