Which airlines do you currently park your miles?

The best way and least miles are not necessarily the same thing. It can be a quality (re:service) vs, quantity (re: miles) thingy.

Are you mainly asking for fewest miles in C from SFO to SIN?

Please keep in mind, not every mile is created equal. Miles in certain FFPs sometimes hold higher redemption value than others. And the value is in the eye of the beholder and/or hoarder.