Go for LH as give you more miles and generous redeem, sometimes they do UG for free as well so being a SEN it shouldnt be a problem, I believe with 100K/Month like that you will easily get HORN Circle STATUS with LH. SQ quite strict and take you a lot of milegae to redeem. LAX-SIN-LAX is very popular route and normally premium cabin being secured very fast although you may get SIN-HYD-SIN very easily.