I've only done one playthrough of V:tM - Bloodlines and I chose Gangrel because Nosferatu and Malkavian seemed to be replay material in my opinion. They may have been less popular due to a similar notion. Most people want to see what the game can offer the most of on the first playthrough. If I replay Bloodlines 1 I'll probably do a Malkavian or Nosferatu because of how different the playstyle would have to be and it would make it more interesting.