Flew everything but the 400. My vote goes to 757. Curiously my second choice might actually be a 321 (or a 2nd place tie with the 777). I was never that wild about actually flying the 320 or 19, but the 321's are rock solid. I am not sure why that is as they should fly similar to the other two, all being FBW.

The new 21's come with up to 34K thrust per side. They are rockets. Clipped wing rockets as the V speeds are a bit high. But you get there very quickly. Landing speeds and distances are lower than the uber guppy.

I would be happy to see the 321LR. It won't do short fields like a 57, but it will do everything else.