10% Resistance reduction is 11% more damage, is how the math works out. Twin Snakes is 10% flat, Dragon Kick is 11%. DK > TS.
It's not if the tank moves the boss in such a way that you miss one, or if you have barely enough skillspeed to do 5 gcds, a slight hiccup of your connection can cause you to miss as well.
Edit: Here's adding some values to that claim, since I might as well show some numbers if we're talking %'s.
Here's bootshine spam for 3:00 without any buffs.
http://i.gyazo.com/40369cea68610a1fb8a0db5b225f3844.png
Average bootshine hit: 362
Average Autoattack: 198
This one is the same, but with Twinsnakes. (Note: Crit Rate was around 5% lower, so numbers are slightly skewed; however, the math still works.)
http://i.gyazo.com/ae6fcbced1b0e8c70d340385a111ecf1.png
Average Bootshine hit: 375
Average Autoattack: 215
This one is with Dragon Kick being fed from another monk.
http://i.gyazo.com/83d7ea9cdd69f7a97ca2a979263fca7f.png
Average Bootshine hit: 395
Average Autoattack: 219
To be perfectly honest with you, the autoattack numbers are the more accurate numbers.
Anyways, the Average is higher with DK, which just proves what I said - DK > Twin Snakes, and that's why you want to put up DK First - it is the bigger buff.