I was on the fence with DL. But, since I've flown many times on DL since covid and their partner Aeromexico who packs their flights with no empty middle seats, the only thing now I find beneficial with DL is nobody will be sitting next to you in a three seat configuration. That's about it. AM has also equipped their planes with HEPA filters, and do the same sanitizing as DL. I don't believe one empty middle seat changes much, other than provides passengers with extra elbow room.