Xotic SP-X mini-pedal. Best compressor for the size. My favorite is the Keeley 4-knob full size compressor. I only use that on my guitar though. I use the SP-X on the bass side of my stick board.

Xotic makes great stuff. Have you tried the X-Blender with your compressor? Will turn your (or any....) compressor into a parallell compressor. Cool stuff. One can squeeze the living daylight out of the compressor and still have the dynamics intact..... Also called New York compression. I use it all the time on pretty much everything. Works great on the Stick, on bass, on drums, as a mastering compressor on the main buss on a console.....

I agree that the Xotic mini sounds great! I have two on my battery driven street busking pedal-board, one for each side's audio output from the Stick. I let the dry signals pass through and add subtle parallel compression. On the Xotic for my melody side pickup output I have set the small switches inside the pedal to cut away some sub-bass, this to minimize leakage from the bass strings into the melody side's pickup - that I want to have a smoother sound that floats on top with what I'm playing on the bass side. BTW, cutting sub-base on the melody side is something I always do in all my amp rigs.

I remember seeing a TC Electronic Nova NDY-1 pedal on someone's board here. The dual channel setup seems made for Stick. It looked interesting to me so I grabbed one for $80 from Reverb. It's discontinued now and seems to fly under the radar a bit.

You all have mentioned that something like a multiband compressor is more ideal for the bass side than a standard stompbox compessor, which can be activated for both channels on the NDY-1. Additionally, both channels have a dry blend option and the attack, ratio, and level can be adjusted as well. I'll report back here once I get it to see how well it fares.

For the price it was just hard to pass up.

True. That's what I've found gives the most transparent sound and I use a multiband (3 bands) compressor in the Axe-Fx (on the bass side, on both sides or and the sum of both sides. All differently sounding). But I always run any type of compressor in parallel, to keep a part of the non-processed note attack.

there's the TC hypergravity s well -- the mini and the full versions are essentially the same - except for the additional panel controls.
but you can map the controls from the app on the mini (you can even map more than one parameter to a control)

it's very flexible - you can chose the (3) band crossover points, there' wet/dry mix for parallel compression and a bunch more

The EBS MultiComp has a multiband setting which works very nicely with the bass side of the Stick. I almost always have it on, I think it makes the bass side sit nicely in our band sound.
I also like the Xotic SP for a little added parallel compression on the melody side.