Why would anyone want class AB amp when class A always sounds better ?

Clearly, there are lovely examples of amps of all description. That said, I still occasionally hear old low watt Levinsen and Krell class A devices which move me to tears. There is something there. Options exist at my house but a Pass XA-30.5 remains an object of my most ardent affection.

The most difficult thing to discern is who listens to equipment, and who listens to music?

Ages ago when there were stereo stores all over the place, I fell in love with new speakers everyday. It's for certain I was an equipment lover then, but that's before I got into "The high end". My favorite tuner was "Sansui", it had a most beguiling sound that was quite soothing, and many people still prefer them to more accurate tuners.

My favorite speaker was first JBL, and next it was the Amazing Carver Speakers;
        https://www.stereophile.com/floorloudspeakers/290carver/index.html
The music had an other worldly quality; "ephemeral", I guess would be the one word description, but at one time I liked "reverb" in my car, that made your automobile sound like you were in a cave.

When I got into the high end, I finally discovered how good the music sounded unadorned without any tricks. Since most speakers have some kind of "sound", I had mine custom built to have no sound of their own, but to deliver the music, the same as a Class A amplifier delivers it to them; without anything added or subtracted from the music, only what the artist wanted you to hear, his music, with each and every individual nuance.

While I mentioned Class A because it is "Theoretically perfect", I can not audibly distinguish it from AB.

One of the problems of differentiating music lovers from equipment lovers, is that equipment lovers will almost never come clean and admit it (maybe they don't know themselves) consequently, right or wrong, I discern who is an equipment lover, and who is a music lover. This is very important when reading Posts.

I like equipment that gives me good sound, other than that I only like tape decks. I don't think that liking good sound and liking good music are always in conflict. They can be but not necessarily so.
Old Levinson ML-2 class A amp is a dream piece.

"I don't think that liking good sound and liking good music are always in conflict."

Agreed

I average approx. 4 hours a day of listening to music through my system when life is "normal" for me. I have not been able to do that for the last couple months due to other priorities, but plan on getting back to it again soon. My amp is an AB (Magnus Audio MA400) & I love it. I've had class A's, other AB's, Triodes, Pentodes, SET's (both tube & SS), & class D. They all sound different & have their plus & minus's. This one connects best with me & my system.    

Schiit Audio 20w Class-A Aegir stereo poweramp made it into the A rating in 2021 Stereophile’s Products of the Year.
https://forum.audiogon.com/discussions/stereophile-s-2012-products-of-the-year
Cheers George