I have a preference for 700C as my all-rounder basis. It has to be:
sport tourer,
gravel grinder,
cyclocrosser,
monstercrosser,
loaded tourer.
So, it must have tire clearance, lightweight, and spirited geometry.
Some higher level hybrids, a Bridgestone RB-T come to mind.
I planned to do a Cro-moly hybrid all-rounder....but have decided to go modern to fulfill this role. Weight was one reason.
The current all-rounder title holder is my mtb-dropbar conversion. It has been subjected to tough conditions. And a tire-swap allowed it to tour around town comfortably all day.