If you are flying alone, would you rather have a Delta Comfort+ middle seat (for the extra legroom, free alcohol, closer to the front, and better OHB space), or would you rather have a non-preferred aisle/window seat? This excludes exit rows.

Edit: I never change a seat without talking to the customer first. (Or if I do, then I block the original seat so that the customer can still take either seat).

My ultimate question is: Should I spend the time figuring out how to fill up middle seats, or just stop after moving aisle seats up to DC+ aisles and windows up to DC+ windows?

It sounds like only a couple medallions actually prefer DC+ middle seats. I'll just worry about filling up windows & aisles.

Aircraft that I work with are 738, 319/320, MD88/90, and 757.