I'm already at NG+ but wants to start over so I can perfect the game in 3 runs (you should be able to do so in 3). I want to know is when I finish one route and advance to NG+ which data do I transfer from: the first complete or the second?

u need to do the game 4 time .... 1) first girl 2) first girl again for the bonus ng+ scene 3) second girl 4) last girl

So which of the three heroine is worth playing a second time?

it depend wat u like loli, average size/tsud , or big breast elf ..... i play yuela first, then loli to get it over with and yuela again then the elf last .....

if u r starting fresh and u go with loli, gl cuz thats the hardest route u will need to lvl up alot
if u r going with yuela, note that the travel is abit long (6 days i think), and she will be ur dps for the rest of the first game and somewat in ng+
if u r going with elf, her ending is the easiest to beat, the boss is in front of u .... just couple of step and focus fire on it ....

If you choose to save the status after finishing Y, then your new game will continue from Y. Otherwise, from X.