I'm a filter junkie as well and DO have personal experience with all three of those. Here's some quick thoughts on them (and on some filters you may not have thought about). I've highlighted your three in blue if you don't want to read the rest.

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Okay... here goes!
Filters I currently own:
3Leaf Groove Regulator - My current favorite pedal. Like others have said, no harsh peaks and very well mannered (in that I always know how it's going to react to my playing). Great thick tone, not bright, but not too dark. SUPER super funky, IMO. The less aggressive sound is exactly why I like it. It fits into a mix well, but isn't in your face.
Ashdown Bass Envelope Plus - Avoid this one. Had to have the input maxed to get it to do ANYTHING. Sound wasn't even mediocre at best.
Barge Concepts MB-1 Grinder - Swiss army knife filter. This one can get you
any envelope sound you want, and is a clone (and improvement) of the venerable Lovetone Meatball, which is quite rare and expensive these days. Downside, quite large and can be pretty complicated to dial in... 7 knobs, 4 switches, effects loop and jacks for THREE expression pedals.
Mojo Hand Analogue 442 Red - Clone of the old school DOD-440's, dialed in for bass. Simplicity in a filter compared to the Barge... level and range. Good thick middle-of-the-road sound and pedalboard friendly.
MXR M82 Bass Envelope Filter - More aggressive sounding filter, can get quite quacky and wet but still has a pretty wide variety of envelope sounds. Two KEY controls... Dry blend for keeping low end in your sound, Decay for getting the filter to close faster if you're going to play quicker stuff (runs, scales, staccato-ish funk stuff). Great sound. Plus, it's purple and it sparkles. hehehe
Subdecay Prometheus - Another filter that's not too bright, not too dark. Don't worry, definitely capable of a "standard" envelope sound. It can get wetter and more intense than the 3Leaf, but has a slightly darker overall tone, if that makes sense. I don't use the Step filter at all really... but it IS a very cool/interesting feature. This one was my favorite until I found the 3Leaf.
Filters I've owned and sold:
Digitech Bass Synth Wah - Solid envelope sounds, with other wackier (in my opinion) modes. I used envelope and envelope octave, the others were throwaway for me. Even with the dry blend, it didn't keep low frequencies as much as I would've liked, but it wasn't TOO noticeable.
EHX Micro Q-Tron - Low Pass mode sounded pretty good, a little bit more on the aggressive filter side. But High Pass and Band pass were unusable IMO unless you are looking for "an effect." Low end was completely gone with those settings. Also, I found it to have a slight volume spike when engaged.
Ibanez AW7 Auto Wah - Has distortion built in, which you can have before or after the filter, a nice touch. Not a bad filter, but not bass specific and therefore DID have a noticeable drop in low frequencies.
MXR M-188 Bass Auto Q - The Bass Auto Q had an interesting mojo to it. The Blend knob isn't for mixing in dry signal, it's for mixing in a "shimmer" effect, and the shimmer could make this pedal sound VERY watery (warbley, not "wet envelope filtery"). The filter itself sounds pretty good, adding in the shimmer makes for some pretty cool sounds. Quite unique.
Other filters I've only played:
DOD FX25B - The guy who owned it pulled up
Invalid Link Removed video, and the FX25B sounded pretty darn close to that. But like others have said, I wasn't terribly impressed with the bypass. The blend knob was the only thing that saved this pedal from low end suck, but that's why it's there, right?

If I found one out there for cheap, I might pick it up for curiosity.
EHX Enigma Qballs - Not quite Swiss army knife, but you can still dial in a wide variety of sounds. It's got distortion built in, which reminded me slightly of a Bassballs sound. Again, High Pass and Band Pass dropped way too much low end for my taste, but Low Pass was definitely tasty. A good solid envelope sound, edging into bright and a little aggressive.
Moog LPF - Not a bad sound, very "vintage." Interestingly, the Drive control is on whether the pedal is bypassed or not. Meaning, you'll have to set the Drive setting before you do ANYTHING else with any of your effects. BOOOO.
Mutron III (LSound modded) - WAAAAAY too bright for my taste, but WAAAAAY Bootsy! Duh, right? lol Tried it with a few different basses, overly hot pickups will open the filter pretty fast, sometimes the filter sweep would get lost. If you're serious about Bootsy, this is the one.
Pigtronix Envelope Phaser EP-2 - Currently #1 on my G.A.S. after getting some time with it. The envelope sound by itself is quite good, not overly bright, but still has plenty of quack and bite available. Adding in some Phaser, which is also good just by itself, will really make your envelope sound sing. Tough to describe though, check out Doug Johns' solo on Chew on a Dog, at 2:21.
WMD Super Fatman - Another Swiss army knife filter. LOTS of controls, with an LFO mixed in. 12 different settings on the Range knob will give you any shade of brightness you want and the LFO will add in anything from slightly swirly sounds to almost tremolo choppiness. Dial in anything you want.
Recommendation:
Of the three you asked specifically about and based on what you've said you're after, I'd agree with Smurf... the 3Leaf isn't what you're looking for. If you can check out the Qballs and M82 side by side, I'd go that route. I think you'd be pretty d@mn happy with the Qballs, but personally... I think the M82 just has a little more RHCP vibe to it. But just barely.
Whew! I'm done. Sorry! lol
Hope that helps at least a little...
5sg.
P.S. Uriah Duffy did a demo of the M82... if you haven't seen it, check it out
here. What you hear is what you get.