I'd consider a PATB-2 Parallel Axis Distortion for the bridge, if you want all-out metal. There's plenty of great options, but that's my favorite. Roaring mids, lots of growl, screams for solos, ridiculous harmonics, and remarkably expressive for such a high output pickup. It's pretty similar to the TB-6 Distortion, but with less harsh a ceramic bite on top, even more mids, and a lore more lower mid growl. Absolutely joy for leads and riffs, though depending on taste you may need to cut lower mids a bit for thrash tones to prevent wool, but that'll depend on your amplifier and tone tastes. Metallica used even bassier pickups like the Invader (though this probably has more growl, vs the Invader's deep punch, though either can be flubby if the preamp can't handle those frequencies. But that's what EQ stomp boxes and tube screamers are for!).
There are subtler pickups, but if you want unsubtle but still musical, there's a lot fewer competitors.
For a neck pickup, depends on what you do with the neck. Given you are looking at replacing your neck pickup, I'm assuming you don't do the cleans from neck, gain from bridge thing so much, or at least you want a neck that can keep up for solos, even if it can clean up when backed off.
For a flexible neck pickup for a metal guitar, a Black Winter neck is a pretty great neck pickup.
A bit more distortion focused, something like the Distortion neck is pretty good, too.
If you want a neck humbucker that can do the PAF/Jazz cleans thing, but with a bit more oomph for leads, a Sentient is a great choice.
