They are not mutually exclusive. Since you were mentioning Spectors, the Euro series have active EMG pickups and a TonePump preamp.
If I was obliged to choose one or the other the fwiw my preference would be an onbaord preamp. I think it's useful to have the control under your fingers rather than wandering back and forth. Plus I use a wireless setup and as we do not have a sound engineer I can hear what the band sounds like in the room, and adjust my bass accordingly without moving an inch. YMMV of course