I live in Alaska, hunting everything from Dall Sheep to the incidental Grizz, with moose and caribou in between. If you owned a 300WSM would you load for the above game 168 TSX's or 180 TSX's. I know all the above critters can easily be killed with either just looking more for suggestions on the 2 different weights and their performance first hand from folks. This is my first WSM and I hear a lot of guys shooting 168's out of their 300WSM's instead of 180's.

With the typical lead core bullet the 180 would be the choice for energy and penetration since they don't retain their full weight. In the TSX bullet this is not the case. It retains all of its weight therefore the 168 TSX will penetrate very deep compared to a normal 180.
My best advice is which ever one shoots the best groups for you. You are only talking 12 gr diffence.
I got a lot of information about the 168 TSX on moose from Boondocks Gun Shop in your neck of the woods. 907-694-2229

168s. You won't be sorry. But the animals you shoot will be!

Well the real way to tell is to get a look at a real good ballistics chart or a program like Sierra Infinity showing not only trajectory but energy as well at the ranges you intend on hunting at. Compare every aspect of the bullet weights performance before you decide based on someone elses hear say.
I did this some years back when selecting a bullet to use for everything in my 30/06. When I did the math and I came up with 180 grain bullets as the cats meow for the best trade off for retained energy and trajectory. As it worked out the gun decided it for me as well by shooting the 180's far and away better than any other bullet weight.
If you don't want to go to all that trouble just pick the one that appeals most to you or shoots the best in your gun and be done with it.
Either of the bullets you mentioned will be very deadly on all game you mentioned out to as far as you dare shoot.