I say 1st left because it actually takes more skill to do all the transitions while running the proper drift line through the course. An to u get a lot of throttle control practice an gear changing in drift while making a smooth u-turn.
2nd left u can blaze in an for the most part you use your momentum to carry you thru the sweeper an then 1 transition an exit.
It is my experiance that 1st left offers better overall quaility practice by utilizing various techniques not used on the "2nd left" course.