Bridge pickup for alder guitar

I'd look for something with good clarity for the low tunings.
try looking through what the big PU-makers offer and search for characteristics that you want.
try Seymour Duncan and Dimarzio, also Bareknuckle and Lundgren if you dont mind spending a bit more
 
with Dimarzio the 7-string PUs differ from the 6-string PUs of the same modell though

but with your favourite sounds in mind I guess Dimarzio would be your best bet, try doing some more research on their models
 
i had a semour duncan jb is a les paul it sounded nice almost every note squealed.i have a dimarizo tone zone in a mohogany ibanez sounds a little weak i think the stock pick ups had more grunt.