I like the US post office, and always use the delivery in 24 hours option.
If you specify an arrival time, say arrival within 24 hours by 10:30 the next morning, to be signed, and the package arrives late, you get the shipping cost back, whether its 24 hours late, or 3 hours late.
And basically, they all use the same planes, just depends on the hub.
And as far as reliability, whether its a Fed-X plane, a commercial flight, or something else, if there is a storm, and planes are late, you're screwed anyway, at least with the .S postal service, you get that portion of your cost back, whether the fish arrives live or dead.