In our PAFs, we use Alnico 5 for the neck and Alnico 2 for the bridge. The choice of Alnico 5 often raises eyebrows, as many people consider that it is too strong a magnet for a low wind humbucker.
We decided upon this combo after years of research, getting hands on with literally hundreds (We think. We've slightly lost count) of sets of original PAFs that we've had the incredibly good fortune to test and/or repair. We've found that the best sounding PAF sets have a fairly strong magnet in the neck and a weaker magnet in the bridge. This keeps a nice amount of clarity in the neck pickup, whilst preventing the bridge pickup from getting too shrill. After testing basically every combination we could think of, we realised that the best way to replicate this is to use Alnico 5 in the neck and Alnico 2 in the bridge.
Obviously it goes with out saying that the choice of magnet is only one part of a pickup's design; the sound of a pickup is created by the interaction of all of its parts, so it's difficult to say that a particular magnet has a certain sound. Our PAFs are built around the Alnico 5/2 magnet combo and we believe that they sound their best when using this combo. That being said, everybody's taste is different; if you're sure that you want a different magnet combo, we would be delighted to custom wind a set of PAFs to your specification.