If you want a filter for synth applications, I would say Manta, Moog, Xerograph, or perhaps the bigger 3Leaf units with the fx loop.
I did a one-off gig at a friend's wedding last year that needed some bass synth so got an Octabvre Mini and Manta, and the pair did a great job. Not so sure I'll ever use those sounds in the band I'm in now, but I'll probably keep both around just for fun!
When it comes to pure touch-sensitive expressive funk filters though, the Discumbobulator is my favourite. You'll know when you have found the one when your face goes like this: