The Double Bass Guide has the most exhaustive list of double bass pickups I’ve ever seen. My particular favorites (not because I’ve heard them, just because they look interesting) include the Schaller pictured to the left, which looks like someone took the hood ornamant off of a 1957 cruise-mobile and wedged it onto the end of a bass fingerboard.
The Wilson has always looked interesting to me, but I’m so afraid of a pickup that requires sending my bridge away for installation. 
It’s also never seemed convenient to spend time with a bass, but no bridge.
I think the most interesting-looking is the Japanese Yamahiko, whick looks a lot like the nearly ubiquitous Full Circle, but convenient in the fact that you can actually turn the wheel conveniently.
I have been very happy with my Upton Rev Solo II, which I’ve had for over a year now. I think, like many bass players, I’d love to have a mic setup, but am happy to find a rather neutral-sounding piezo system to fill in the gap.