I have three -- maybe four if we count a Patching Panda Punch. A 4MS PEG, a Make Noise Maths, and a Velectronic AEnvelope. I also briefly used a Befaco Rampage, but had the option to keep that or the PEG, and chose the PEG because it seemed a little clearer and I liked the layout better.
The Maths I picked up pretty recently and am still warming up to it. It's perfectly fine and I like it.
But as a general EG that gets talked about less, I've always really loved and still love my 4MS PEG. It has a lot of overlap with the Maths, but has its own depth, and it's a much more intuitive, clearly-laid-out, easy-to-get-into module. For me the Maths definitely doesn't replace it, but does offer a different (if somewhat more convoluted) take on similar functionality. You can probably go a little deeper with Maths due to the inclusion of the OR/SUM/INV section, the 4 available channels, and the inclusion of onboard voltage offsets. But then again, the fact the PEG has a pair of onboard quantized clock multiplier/dividers has always been a pretty great feature, to me, particularly if you have a QCD, which the PEG will sync to without any patching if it's on the same bus. There's also more variety to the curve shapes you can apply to the envelopes of the PEG, and either channel can be independently selected to be unipolar or bipolar, with an additional unipolar +5V out dupe. And while the PEG retails for more than the Maths, secondhand you can often get them cheaper than Maths.
I think a Zadar could be super interesting, but I feel like I wouldn't get on with its digital, menu-driven nature. I did some of that with an O&C and never cared for it much, though I'm sure the Zadar can do way more. Where the Maths seems kind of opaque until you get used to it, the Zadar seems too menu-reliant. (Just for my own taste -- I've never used one, so I'm not sure, and Xaoc makes some good stuff). If your primary concern is being able to create very specific envelope shapes straight from the module, and you don't mind little menus, Zadar is probably a good pick. Coming back to the PEG again, though, I really like the balance it strikes between being (relatively) easy to "read" (and thus patch/manipulate), while still being primarily tactile and knob-driven. The Maths I have to kind of pump myself up to utilize, at least right now as I'm still getting to know it, where the PEG I've always just immediately and intuitively reached for. If I didn't have a DATA to better visualize what Maths was outputting, I don't think I'd be too crazy about it. It helps with the PEG too -- a DATA is great all around to have, really -- but doubly so with Maths.
And as for the AEnvelope by Velectronic, I absolutely love that thing, too. It's kinda niche, fairly expensive, and not unlike Maths, takes a bit of work (and tutorial viewing) to get your head around -- but once it all clicks into place and you get the feel of using it, it's really great. It's actually pretty easy to use once you walk through its features, and I don't feel the need to pipe it through my DATA as much as the others -- it's just a little intimidating at first blush. My only nitpick really would be that I always find myself wishing the second row of outputs were inverted or polarized outs -- that would make them more useful to me. But it's a minor quibble. And aesthetically speaking, there's no contest, it's a truly beautifully designed module.
And while we're talking ADSRs, I also had a Doepfer A-141-2v that I've always vaguely regretted selling. It only offers one envelope, which in my experience wasn't the snappiest in the world, but you get a lot of control over that envelope, with some interesting self-patching options. It was actually pretty interesting as a weird oscillator when self-patched. I've tried that with my PEG as well, but I feel like the Doepfer rolled with the audio-rate abuse a little better than the PEG does, you could really get it to sound like its own voice. I imagine like other Doepfer ADSRs you can get these fairly cheap, I know I sold mine at a pretty big loss secondhand, which is one of the reasons I regret selling it. And while I've never used them, the Doepfer A-140-2 and A-143-2 both seem like tremendously good values relatively to what you can get them for secondhand (or even firsthand, really).
I can also recommend the Soundforce Dual ADSR, which was what my AEnvelope replaced. I'm 100% happy with my choice, but the Soundforce was perfect while I had it -- nothing too fancy too it, but always absolutely clear at a glance with its dual slider set, good responsive envelopes, good support from the company. It's a bit big for what it does, but if space isn't at a premium and you just want something useful and easy, it fits that bill nicely.
