Why do I like Class AB better than Class A?

Minor1, there are some amps out there that have a switch between high bias (Class A) and low bias (Class AB). The OP's Plinius SA-100 mk III is one such of these amps. Clayton Audio also had amps that used to do this. There may also be others that I'm not aware of. So you have the ability to switch between Class A operation and Class AB operation via a switch on the amplifier.

To answer your question: Compared both what?
He compared both forms of operation (A vs AB) that his amp is capable of. Yes, there are other forms of operation such as Class D, also.

marketing. I would bet you a lunch that the Plinius is biased class A up to a particular bias point and even within class A/B and when you flick the switch the bias is reset to a higher bias point.

enjoy

Got it. Still once you turn a transistor on, it is on. It can be turned on at a really low bias point, but, it is still on. Then you can really turn it on at a much higher bias point where you are cooking at full rated output without an input signal.

This is marketing and semantics. But on is on. Some devices are biased such that they aren't turned on until the AC signal is passed through it. Others are biased such that they are turned on with DC bias with or without an AC signal passing through it. Again, many of the amps I have tested and repaired state they are class A on the specifications and are rated at 50, 100 150,etc. wpc. This does not mean that they are biased at the rated output capacity. They are biased on at 2 watts or 5 watts of 20 watts etc.

also, thanks for the clarification. I didn't know this amp had a switch that altered the internal circuit bias. However, to be clear, all it did was change the bias point from a lower to higher output driver bias. Which is a good circuit design idea as long as you have the power supply capacity and the proper heatsinking for the output drivers. Full output class A is wonderful for those cold days and nights when I want an extra space heater. Tube amps are also good for this.

enjoy

I don't think Plinius designed the SA10x and SA Reference/250 to be Class AB amps but they wanted the amps to be left on all the time, so providing that AB switch provided owners a way to leave it on 24/7 without busting the electricity bill.