It depends if one's a Carver from the 80's in Class A, and one's a set Marantz Mono's in AB, I'd go with the Marantz. It all depends. A/B is the ultralinear circuit, which has slightly lower losses and higher power. Class A has slightly less efficient power, higher lossyness in the circuit, and a lot of the time still makes better sound through brute force.
Two amps, one pure class A, other A/B
Here is the question.
You have two amps from the same manufacturer, they have the same power supply, the same transformers, most likely the same output transistors.
One is biased as pure class A and outputs 50W.
The other is biased as class A/B and outputs 150W.
If 50W amp clearly cannot drive your speakers (you have flabby bass), will the 150W one do the better job, considering the only difference is bias?
You have two amps from the same manufacturer, they have the same power supply, the same transformers, most likely the same output transistors.
One is biased as pure class A and outputs 50W.
The other is biased as class A/B and outputs 150W.
If 50W amp clearly cannot drive your speakers (you have flabby bass), will the 150W one do the better job, considering the only difference is bias?