Those two pickups have been my favorites for years and at this moment, both sit at the bridge position of my two humbucker-loaded guitars.
I've had them in alder, ash and mahogany guitars. JB loves alder and ash, the Demon loves mahogany. But that's not written in stone because each guitar has it's own thing.
You just have to try.
For 80s metal the JB is better than the Demon IMO.
Leads are thicker and because it has more mids and output, it crunches more easily than the Demon, which sounds more open and it's less compressed.
For classic rock the Demon should be better, particularly if paired with a vintage-style overdriven amp or pedal.
The JB is too hot for that and not open enough, so it will be mushy and flat, while the Demon's clarity will cut through the mud and make everything sound OK.
If you style has lots of distorted chords, particularly with voicings like 7ths, 9th and what have you, the Demon will win because notes are very distinguishable with it,
whereas the JB will turn to mashed potatoes with that sort of playing.
If you're gonna pummel power chords and flashy solos away, you'll like the JB better.
For more elaborate, varied playing and a more unique sound, you'll love the Demon. But you'll have to play a bit harder because it's more unforgiving.