OP's opinion Delta's is "the absolute worse" just depends on what you are trying to get out of it. If you were always first, would that be the "absolute best?" But then, isn't it now the worst for someone else?
Seems to me that just the current method is no more or less efficient than any of the other suggestions. Fairly random group of people asked to get on at various intervals.
The really efficient way would be to have folks with a window seat in the back board first, then windows in the front, then middles, etc. IIRC this was how it was a long time ago.