here are my opinons

LS and B20 not may fav i don't like stroke

B16 i believe that terry proved that myth wrong that they don't put out power PM him or me if you want info about them

GSR motor strongest factory B series great motor

H series i hate them i don't like them at all the H22 i hate the tensioner i hate the FRM coating, i hate how they chew up oil pumps.

Go with a B16 or GSR you can find SiR front clips for a pretty good price and that is everything you need right threre (minus harness wrong side of car)

your next question is do you want a hydro or cable tranny (i personally like the feel of the hydro better)

Also how much money do you want to spend?