I would still zero out the EQ first, the center frequency on the control should be in the user manual, as a reference, targeted boosts or cuts might can do it for you.
As far as pickups, most sites have a sample of what they sound like, since it's subjective, I can only tell you I went with Aguilar's over EMG, Seymore Duncan, Fender, Bartonlini, Dimarzio, Nordstrands etc...
A jw23mind is correct about a good preamp. It's less invasive than modifying the bass, easier, and may cost less. As a step that would be the second step I'd take with # 1 being EQ and Setup of the bass and rig.
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For Preamps, you could take a look at preamps with a DI built in as some gigs require no amp/cab on stage, so you're going to need one anyway. I use TC Electrics Spectra-Drive as it has EQ, a Compressor, and Overdrive, plus a DI balanced out, and you can program it with different sounds via toneprint. So if you need it darker, you can reprogram it.