I have Bartolini NTMB-918F in one bass and Audere Jazz in other. I think highly of Audere,
see here.
Bartolini is older version on 3-eq 3-mid knob discussed here. The sound of Bartolini is very clean, usable, quick to set right. I would describe it as 'no miracles, just a reliable, practical tool that lets the bass sound natural'. Lately I soldered off the blend pot and am using it now with my P. On that P I got flats, which is by no means a good way to judge sound of a preamp. With this said, I can add my personal characteristics: the best results with Bartolini preamp I got when tweaking highs. Mids are alright, but somehow the untweaked sound sounds usually best. Lows can be tweaked nicely, the overall sounds doesn't tend to be unnaturally boomy when turned to max.
I should add that the Bartolini preamp is some 10 years old - likely more, I'm afraid to count it

- and still no rattling pots.
The main volume knob of Bartolini preamp can be lifted up, in which case the bass goes passive and even works without battery. I have a feeling this is very important, as I can compare the passive and active sound. With my P, the passive sounds better at home; I never used passive at a gig however. I guess the practical advantages of active preamp (you can go straight to mix, you can take any cable that lies around, etc.) outweighs the nicer, thumpier attack of passive. My opinion only, of course.
Audere does't work without battery at all. The philosophy behind it is 'battery lasts so long so why should you want to go passive?' This is a real disadvantage to me. But, the sound shaping possibilies of Audere, with the super flexible Z button, makes it great.