Magnets have no sound/tone in and of themselves. They simply provide a field of a certain strength. That strength combined with the coil design/s either gives you a tone you like, or it doesn't. Any of the common pickup magnet formulations can be OK if the pickup is designed around the strength of that magnet. When you insert a magnet into a pickup, and that pickup was not initially designed around that magnet, sometimes you get something great, and sometimes you get something terrible.
Point being, it doesn't make a lot of sense to write off any one of the common types of pickup magnets across the board, in and of itself. They will produce different sounds with different coils.
I chose A8 as the "pump" for a very low wind unequally wound Gibson sized humbucker that I made. I filled the coils with 40 gauge wire. 6,200 turns between both coils, which is about 3/4 the number of turns on a typical vintage style Fender guitar pickup. The theory was that the extra strength of the A8 would make up for the relatively low number of windings on the coils. The pickup sounds decent to me. It's clear and bright, but not as weak as you'd think.
But putting an A8 bar in a pickup the coils of which were designed around the strength of A2s–A5s might result in too much compression up front for my, and many others', liking. The pickup was not designed around having that much magnetic strength pushing it, so you might get output and frequency effects that don't really sound "good," as an engineer would design them. But if that same engineer had started out with a magnet as strong as an A8 being the case, he/she could have designed ideal coils to work with it in a "pleasing" way.