Hummm...
trouble with trying to give a 'ball park' type set of numbers is that no-one ever agrees with anything..
has to do with the "volume" payload as well as the "weight" payload. The volume payload is determined by the way a carrier handles the baggage issues and how well those are handle - a carrier with a well-tuned system will release "baggage" capacity to their cargo colleagues in time for the cargo side to take advantage of any increase. Carriers with badly-tuned systems sit rigidly on their baggage capacity right up to close out (and then blame the cargo people for not utilising all the spare space, been there ...)
Effectively a flight starts its life in the CRS at 1 year ahead, assumes 100% pax LF and that determines the nbr of containers for baggage and then what's left is allocated to cargo.
So on a 744 that might mean that cargo is allocated 5 pallets (usually) plus 4 containers.
using "average" cargo densities roughly that translates into 5 x 2,500kg on pallets and 4 x 1,000kg in containers
So thats 16,500 kgs.
A well-oiled system will gradually change the baggage ratio releasing volume to the cargo side.
But as a very rough guide on a 6000kms sector, none of the widebodies is going to be payload limited these days.. so here goes from experience
744 16,500Kg
777-300 19,000Kg
777-200 17,000Kg
A340 18,500Kg
A330-300 18,500Kg
A330-200 15,000
787 still only the little one but around 16,500Kg
A380 16,500Kg (it seems a bit of a strange beast under the floor)
B767-200 10,500
B767-300 14,500
all to the nearest half tonne
These are averages on "good" cargo sectors from various sources.
I could go into detail, but that costs you money....