I've been on filter hunts for years and always keep coming back to my Electro Harmonix Mini Q-Tron's. Big boxes which is a pain in the butt, but there's just something about them that makes it all worthwhile and I just can't find in other pedals. Had a 3LeafAudio Proton, an EBS Bass IQ (twice), an EHX BassBalls, an MXR Bass Auto Q, DigiTech SynthWah and probably more that I've forgotten.
My one reservation with the Mini Q-Tron is that, like so many EHX pedals, they're just not the most reliable. (The volume spike issue is easily resolved with a volume pot mod). So, what's been satisfying me the most lately, and available brand new for the measly sum of about £68, is the Carl Martin Classic Optical Envelope pedal. Makes me smile. A lot. Not well known - couldn't find any bass videos on Youtube. Already have a Carl Martin Optical Compressor and love it, so took a punt on the Envelope pedal - was so not disappointed.