Spin & Drain at once
I think for most mechanical designs, the simpler the design the better. Fewer moving parts probably means less expensive to build and probably more durability and less repair. I think the Maytag transmission was really elegant. Turn the transmission in one direction, you get agitation, the other, spin and drain.
I think the spin-drain is better. As someone mentioned I think he keeps soap from settling into fabrics, and it seems to spread the clothes more evenly up and down the tub as opposed to letting all the clothes rest at the bottom before spinning. I imagine that with the clothes more evenly spread around up and down the tub that the water extraction is better, and perhaps the spin-spray has a better effect since water doesn't have to pass through as think a clump of fabric.
I miss my Maytag Dependable Care!