RE: elk bullet in 06
Go to a good hunting store with a decent selection. Buy 1 box each of TSX, Partitions, Accubonds, and any others you can afford. Then go shoot them at the max range you expect your hunt might involve.
Whichever shoots the best out of your gun is the winner as most of the top quality bullets will work on any elk. It's not so much in choosing the best bullet available, but finding one of the good ones that will shoot well in your rifle.
Good luck!