I like the Stereo Clone Theory for bass more than I do for guitar. It nails the Peter Hook Joy Division tones IMO. (Well he used the original Clone Theory.)

The wet signal is tuned to be very bright though, and you might not find that desirable for bass.

The Small Clone sounds quite fetching on bass, the kind of tone that you can use clean for super lush passages or distorted for fat, spacial lines. Super versatile and it’s got the classic vibe, very cool. This effect makes me think of the Beastie Boys’ “Something’s Got to Give,” rad. This one gets points for being the quietest EHX chorus, as well as being the most simple to get working. The best ‘straight ahead chorus’ tones in the Polychorus sound like the Small Clone, which says something about how good this box sounds. It’s the one if you’re looking for something simple to click on and off.

I’ve always had a thing for the Polychorus, myself. It can do all the Small Clone stuff but then there are 10,000 other sounds available. The flanger mode sounds really neat on a clean bass because it’s so subtle and trippy, and in the chorus mode you can dial in a slapback echo as well. I know several bassists who swear by the Polychorus, and it is by far the most versatile of the bunch. Also it is the only chorus pedal that has ever actually made me think two guitars were playing, usually they all just sound like someone is using a chorus pedal. The controls are a bit finnicky at first but once everything starts to make sense, you’ll never want to shut it off. The feedback control is the real winner here, and this box actually gets my vote for the first one you should check out. There is a lot to learn here so go somewhere with a return policy and bring it home for a week or two, that’s the only way to really get into this pedal.

The Clone Theory sounds wonderful as well, but it loses out to those two for one reason: I tend to set my amp fairly bright and then kill the top end with the tone knob on my bass. This leaves me wide open to the oft-complained about noise present in the Clone Theory. If you’re running a dark amp that will mask the white noise in the higher frequencies, this is probably the clearest chorus you will ever hear. It actually allows you to cut through a mix on most settings, and it can get the bubbly Small Clone sound as well as the ‘frosty whisper’ chorus tone prevalent in the 80’s. The vibrato mode sounds cool but a little odd on bass, although with the depth down and the rate up it sounds a little better. Also, you may just think it sounds great so who am I to say?

None of these pedals cut a significant amount of low end, at least not to my ears.

The EHX boxes are the only ones I have ever played with a bass, although I can say from guitar experience that the MXR chorus is worth checking out if a local shop has one in stock.

Anyhow, hopefully it helps!