Tough call. How do you choose between:
(a) something that might determine the difference in your life, economy, rights, and/or world-wide nuclear war.
and
(b) something that has no importance other than fleeting entertainment.
I normally would normally say option (a) hands-down. But, the debate will be covering the news and social media non-stop for the next week. And the game, since it has no practical meaning at all will be gone the instant it ends. For that ephemeral reason alone, I say you should go with the game. The debate can and will be forced down your throat later.
I, on-the-other hand am still stumped by ABC's schedule. On my phone it says DWTS airs after the debate. Which doesn't seem realistic. Why play one of their top shows after half of their audience is in bed and the other half is in a fury from the debate? I think their online schedule must be backwards.