| I've always been happy with Seymour Duncan Basslines. The Quarter Pounder in particular can liven up any wimpy sounding P bass. They can still get that tried and true P sound with a bit of EQ. Probably though, your choice of strings on a fretless is the most critical component. I like Thomastic flats. When the bass is properly set up for these strings and they've been played in for a week or so the sound is, to me, wonderful, rich and melodic and unlike any other flatwound or roundwound string. You might have a different opinion. I played fretless exclusively for many years through the 60s and early 70s. I wish the Thomastics had been available then.
Getting back to pickups though, try as many fretless basses as you can and note what the difference in pickups are. Then you'll be better informed to make a choice based on your own preferences. | 
