howling fist does the most damage. simian thrash and dragon kick do similar damage, but simian thrash is on a longer timer so you probably want to use it before dragon kick (in most situations) to make sure you can use it more. so you're probably looking at howling fist combo first, then simian thrash combo, then dragon kick combo.

always put blood for blood and blindside on howling fist. as far as keen flurry, well- that depends.

you basically have to look at the estimated length of the fight. if using keen flurry on howling fist means you can get in extra howling fists before the end of the fight, then it's a no-brainer. however, if using keen flurry on howling fist won't technically net you any extra total howling fists, then you have to start looking at other ways to use your keen flurry to maximize dps.

simian thrash is on the same cooldown as howling fist, so generally if keen flurry won't net you any extra total howling fists- it won't do any good to use on simian, either. next you look at dragon kick, which has a 60 second cooldown. if using keen flurry there will net you extra dragon kicks before the end of the fight, but not extra howling fists or simian thrash, then you use it on dragon kick.

if you won't net any extra dragon kicks overall, either, then you start looking into your half-combos. aura pulse, concussive blow, etc.

tl;dr howling fist is your big gun and gets buff priority, but doing a perfect rotation for optimal dps relies heavily on optimizing the use of your cooldown timers to squeeze in as many total WSs as possible before the end of the fight. that means both clever use of keen flurry (and the TP you get from quelling strike) and doing your combos in proper order so the cooldowns line up best.