Re: What produces better harmonics?
If you want to thicken up a thin (especially floating vibrato bridge) guitar, something out of the Parallel Axis series is wonderful.
I have a PATB-1b in my RG570 which gave me all kinds of trouble with other pickups (JB, stock Ibanez, wasn't impressed with DMZ/IBZ pickups in slightly later versions of the same model, either).
Parallel Axis is designed to give reduced string pull, higher output, increased sustain, better string balance, more articulate, expanded harmonic response, softer attack (but ridiculously dynamic, feels much less compressed than similar output pickups typically do). Tend to be ridiculously responsive to pick articulation, nevermind tone & volume knob adjustments.
If you want a monster distorted pickup with crazy harmonics, PATB-2 Parallel Axis Distortion is insane. Riffs comparable to Invader, but without losing the high end. Thrash slightly thicker than TB-6 Distortion, but not quite as harsh a bite. Leads have a hint more JB flavor, but with higher output and far more mids.
The PATB-1b is really hard to describe. Very balanced pickup. Mids aren't excessive, extended treble but without harshness. Seems to be the PA version of the Custom 5, but has behaviors more similar to a Custom Custom or maybe an S-Deco (haven't played an S-Deco myself, but I can hear a similar mid grain and singing tone on some samples). Amazing all around rock pickup.
PATB-3 Blues Saraceno is most comparable to a '59b, but higher output without losing the highs. Beefier without bloat, awesome pickup, best bridge option in (non-Custom Shop) Parallel Axis lineup for cleans or low gain. Medium gain it's about even with PATB-1b (both have slightly different tonal strengths there), and past that PATB-1b and PATB-2 edge it out. That's a rough generalization, individual playing styles and tastes of course vary. Some people prefer a lower output PAFish pickup for everything.
(There's also a PATB-1n for the neck, and the Custom Shop Crazy 8 and PATB-78 for more expensive bridge models.)