Having seen both, that's a tough call cause they're both wildly different. I was deeply satisfied with Logan even though the ending left me kinda feeling empty, but the Dark Knight is still the perfect superhero movie to me. Then again, I've seen it a hundred times, so maybe a few more goes at Logan will soften me up a bit.
Still, I would love to see that faint Oscar buzz I'm hearing pay off. We'll just have to see what comes out this year.