Locking Blade: Buck 110/112.
Most slipjoints are also pretty ergonomic.
Examples:
Stockman, Canoe, Barlow, Trapper, Moose,
(large) Sunfish, SAK.
While not a slipjoint, (its a friction folder) the Opinel is pretty ergonomic as well.
Fixed Blade:
Mora with a Birch handle.
Pretty Much any with a stacked leather handle.
Pretty Much any Buck 100 series.
I know you asked for one but I don't EDC just one knife. On any given day I'll have the 110 and a couple slipjoints on me.