Don't get me wrong!
If we are talking about regular production pickups and that classic PAF tone, I have no doubt: 59's have some magic complex sonic textures that I cannot find in 57's or PAF Pro or other PAF-like pickups I checked.
I cannot compare them to other SD humbuckers (PGs, C5, CC, etc).
I love the 59'. The 59' neck is a raw sounding pickup. If you have a nice tube amp, in its sweet spot, when the tube begins to break, randomly, some notes explode as fireworks; the sounds seem to be boiling inside, moving in different directions and, from time to time, a sonic bubble explodes on the surface, feeding the tube at the right level, with a beauty that makes me smile full of satisfaction.
The only that I don't like in the 59's is that can be confussing, played under gain and volume at full. Notes are not well distinguished when playing chords under medium-high gain. Not very clean notes when played on clean mode. This pickup in series with other humbucker becomes absolutelly muddy an dark (if not splitted).
I find the 57' very nice working for classic stuff, it does 70's rock absolutelly well but, hasn't that raw growling sonic bubbles that the 59' has. Has a very previsible sound (works fine, no magic).
In the same league, I find the PAF Pro. Neat work but, no magic, sonically plain.
I HAVEN'T TRIED ANY CUSTOM pickup from Dimarzio, Gibson or Seymour Duncan so, I cannot compare BK to them, only to regular production pickups that I also tried.
IMHO, with the mule, I am getting that magic that I love in the 59' but, that magic sonic bubbles seem to explode in several directions, not only on the surface (that's what people means with 3D sound). The notes are clearly distingishable at any gain level. Every string is clearly heared.
Both BK work fine, splitted to any coil (with distinguishable different voice for each coil), out-of-phase and parallel/series with the other.
Every alternative wiring seems to have an usable sound.
And then... it cames my personal experience (as said in other forum).
I mounted those pickups in an LP-like guitar (Prestige Heritage Standard) with my "Hermetico's LP Exchanger 3" wiring mod, substituting a 59' neck (that I loved a lot) and a JB (that loved/hated).
I tried the guitar in a practicing room (in a building that has a pool of practicing rooms), as I already did with the same guitar, same amp in same building but different pickups.
In a rest moment, I heard someone knocking the door. The band that was in the room at left hand of my room wanted me to join them. They said me that this was the SECOND time that they were knocking the door (I was so excited playing that only heard my pickups, LOL).
Tried with some VOX modeling amp (emulating Marshall JCM-800, surpresivelly nice sounding!!!), with some solid-state amps and with my Koch Studiotone combo. The pickups sound really plane and lifeless with the SS combos, worked very very well with the modeled JCM-800 and absolutelly magical with the Koch (all-tube, class A).
Has SD a CUSTOM humbucker that sounds as good or even better than these two BK's?. Probably yes, dunno.
Has Dimarzio a CUSTOM humbucker that sounds as good or even better than these two BK's?. Probably not, dunno.
Has Gibson a CUSTOM humbucker that sounds as good or even better than these two BK's?. Probably yes, dunno.
Have other boutique manufacturers a humbucker that sounds as good or even better than these tow BK's?. Probably yes, dunno.
I wish I can test every pickup in the market (for free, please, I have not money enough) but, by now, I found my wanted sound.
So, I can only share here my personal experience, guided by my personal tastes. That's all.