American hardware offers the largest load. P-38L, P-47D-40, P-51D, F4U-1D and F6F-5 all haul 2k in bombs at the minimum, plus rockets. The greatest ordnance hauler in the P-47D-40, with two 1k bombs, a 500 pound bomb and rockets. P-38L comes next.
Tiffies can haul two 1k bombs OR rockets, not both. Mossies can haul four 500 pounders or two bombs and rockets. Bf 110G-2 can haul two 500 kilos, plus 4 much smaller bombs. What these three lack in under-wing load they make up for in cannons.
The A-20G can carry eight 500 pound bombs.
All of the above are highly effective and can certainly defend themselves ably.
My regards,
Widewing