[quote name='EssentialTension' timestamp='1449946584' post='2928314']
It's the guitarists not the pickups.
You just need a different guitarist(s).
[/quote]
My guitarist uses whichever guitar he fancies on the night and he has a few of them. Singles, 'buckers, P90s. He never struggles with muddiness or harshness. He just tweaks the amp and pedals accordingly. Some may struggle to feedback when he wants them to, but that's probably more due to the actual room rather than anything else.
I think the OP's guitarist(s) need to learn to control their equipment. The manufacturers put knobs on amps and pedals for a reason