The b16 is the lowest and what most people want because it makes your car faster although some people hate the hight fifth gear so they have the higher geared ls fifth put in the b16 trany. The gsr is the in between the b16 and ls in gearing . It is also a good choice to people that want to be fast but dont want that low a gear . ls tranny is what most people buy when they cant offered the other two lol. It is also a good tranny just alot higher in gearing and would kinda defeat the purpose of going h2b lol.