I doubt that there's any significant difference in torque between the two motors. The Xiongda already has a very high reduction ratio and a top speed of only 20 mph. The only way the Bafang could make more torque is if they had an even bigger reduction ratio, but then it wouldn't do 15mph with a run-down battery.
FYI, there's a 48v version of the tiny Xiongda motor that presumably makes a lot more torque than my 36v one does, though even with only 11 amps, the 36v one isn't bad.
Heavy/unfit riders shouldn't be looking at these tiny motors. There's no advantage for them.
From the picture, it looks like the Bafang is sensorless too, so no nice KT controllers for them either. Most likely, they'll perform exactly like the Xiongda except that they'll be more expensive. The only good thing would be if they do a cassette version, but that would have to be even smaller, so less power and torque.
