Getting back to the C-47/C-46 and were there any competitors.
Well, the post war period covers a few years
Convair delivered their 100th Convair 240 in Jan 1949.
According to one source they could cruise at 291mph at 16,000ft using 67% power (178 gallons an hour)
The ex C-46s were cruising at 215-225mph at 10,000ft using 180-190 gallons an hour (60-67% power).
They could obviously cruise a bit slower and burn less fuel but the Convair was going to go over 25% further on the same fuel.
A converted C-54 or new build DC-4 was supposed to cruise at 239mph (75% power) at 10,000ft using 225 gallons an hour.
A pre war DC-3 with P & W GR-1830 S1CG engines (1200hp for take-off and 1050hp max continuous at 7500ft) was supposed to cruise at 204mph at 7500ft and burn 105 gallons and hour doing it at 75% power.
I would note that Douglas did a lot of refurbishing of the C-54s themselves while it seems independent companies did most of the conversion/recertifying work on the Curtiss aircraft.
What was available when and what prices could influence things but the C-46 didn't have good operating economics unless fully loaded.
figures are from Joseph Juptner's series "U.S. Civil aircraft and could well disagree with what is in manuals.