Party activists are more influential in the primaries. The black-and-white anti-third-party logic applies much less in those elections. The best possible choice is clearly to pick a party and get involved in its internal politics, and not wait until the general election to do anything.

Revolution from within! (Oh, wait, that's what happened with the Republican party starting in the 1980s.)

But that that's not as easy as ticking off a piece of paper and assigning blamelessness.