OK I'll give you my two cents on this.
If you count filter banks into this then two honorable mentions are the Res EQ (wait for v2, it will have CV control) and Monotropa (mine has a mod for tone control inside the feedback path, a "baxandall tilt EQ"). Those two are absolutely nuts. Especially the Res EQ is very non-linear and sounds gnarlier than anything else. You move only one band and the whole sound changes. Turning up a low band can make the sound brighter and vice-versa. It's completly crazy, you need to try it. Both are absolutely mental for feedback patching. If you decide for a Monotropa please buy it from RTFM on modular grid. He will build you one for a very fair price with the tone control mod that I mentioned. It's AWESOME!
The best dual/stereo filter for pinging, oscillations and FM is the Blades right now in my opinion. You have CV over the filter mode, routing and resonance. Especially resonance CV is a feature I absolutely love, every filter should have it.
The best bang for buck filters with a character are the Bastl Cinnamon (harsher distortion, square-wavy) and the Doepfer Wasp (bubbly, with a slight fuzz from transistor distortion). They both sound amazing. Feature wise the Cinnamon has more to offer, it has VCA in it as well. Sound wise I would prefer the Wasp. Theres no filter like it. Even the clones don't sound quite like it. The Dual Wasp from Haible did not have the same sound unfortunately. The wasp filter can make these amazing bubbly, wet, water droplet type of sounds. Pairs perfectly with a benjolin and some reverb, love it. Highly recommended. You can get one on the used market for 50€, absolute no-brainer.
Now for my favourite filter category: Slope Generators, the most versatile filters out there. One of them is Inertia by New Systems Instruments. I think it has the most impressive function density I have seen on a filter. It can be used as V/Oct-tracking oscillator, filter, slew, envelope generator, LFO, frequency divider, phase shifter, envelope follower and phase-locked-loop. The thing sounds absolutely crazy. The filter sounds that come out of it sound very "saw like". Like stepped or spiky, razor sharp. Beautiful module, phenomenal sound. Expensive but totally worth it. Very rewarding when experimenting and useful both as utilty, sound source or modulator.
The other slope generator I want to mention is the Quad Slope from CGS. That thing is totally bananas as well. Using the inputs of the envelopes for filtering essentially makes it a quad filter as well. Whats special about it is that the boundaries between what is an LFO, what is a filter, what is an envelope and what is a slew are disappearing. Super fun to crosspatch the envelopes, it makes one "filter" or "envelope" modulate another one for example. You can do that with all four of them. Ranging all the way from sub-audio territory (LFO range, slewing) to audio territory (oscillator, filtering). Super fun to do. I wish it had a "cycle switch" tho. You need to patch the TRIG OUT to the TRIG IN every time to get it to cycle, pretty annoying. Best envelope out there tho.
The only filter that I really want to try still that is also completly crazy and that I will 100% buy at some point is the Sprott from IFM.
Since I have never used it I cannot comment on it but it's a chaotic filter that plays with the "bounds & bounce" theme that Peter Blasser introduced. Maximum GAS for me :)