Die Duo V

You and your friend are both rolling $6-$sided dice. Both dice are fair in the sense that each side appears with probability $1/6$. You each get to select the sides of your own die under the following conditions: All values must be between $1$ and $6$, inclusive of both, and the die must have sides that sum to $21$. The winner is the person who rolls a strictly higher value. What die would you select to maximize your winning probability? Enter the values of the die in non-decreasing order.