I have a love/hate relationship with chorus for bass. It's a wonderful sound, used selectively. On the other hand, there's all those Jeff Berlin jokes...
My current chorus of choice is the one that is built into my Crate BT350 head. I like not having to deal with cables for FX, and it is a pretty nice sounding circuit. I had a Boss CEB-3 for awhile. Solid unit, but it didn't really blow my skirt up. Still the BEST, however, was the one that Fender built into the M-80 Bass combo I had back in the 90s. I don't know what it was - the schematic shows nothing really special about it - but that thing sounded HUGE onstage. I had a guy who worked for Eventide come up to me at a gig and ask what I was using, because he thought it was the nicest chorus effect he ever heard on a bass. He was dumbfounded when I told him what it was. I've been looking for another of those amps (or the head version) on the cheap for a few years now, simply because of that chorus. The amp itself was no big deal. Even thought about having somebody build be a stompbox via the schematic...