I've had a Bartolini 2 band and an aguilar 3 band and I had the aguilar for much longer so this isn't a completely fair review.
I would describe the aguilar as sharp, agressive, versitile, Sensitive controls.
Now here's my descrepency of the aguilar. When set flat nearly everyone says its just like passive. That was not my experience. Now the non musician probably could tell the difference, but there was a noticable attenuation of the high end. There was a loss of growl from the pickups. One of my friend's was playing my bass recently and said it sounded better without knobs.
I would say the strongest point of the aguilar are the mids. There are so many useful sounds by just changing the mid level and freq. I would say the weakest point is the bass. To my ears there is no subtlety to the knob, a little goes a long long way. Despite my experience most people love the aguilar OBP. Two of my friends are completely sold on the OBP-3.
The bartolini sounds more neutral. The bart tone control seems more to boost or cut the qualities of the pickups. I don't have too much to say about the bart. I only had it for a week or so, I had to get a 3 band immediately.
I recently decided to go with an EMG BQC control. Every review i've read seems to support exactly what I am looking for. It has variable mid control, and 4 selectable high freq. They also offer an active blend but for an extra 40 bucks I might hold out for later. Hopefully it will be a good match so I can get some knobs back on my bass.
PS there's enough info on these two pre's on talkbass to make your eyes bleed.