I’ve got a lot of them. I started out with the Thomas White DIY version, and have 4 of those in my 5U system. They’re all a bit different - I made no attempt to match the vactrols between the different ones so they all respond uniquely. I did put a really slow vactrol into one of them, which makes it really nice for filter use. These all have feedback added, which is an interesting bonus. I also built a few of the one Craig Lee designed - it’s a slightly different version, with a different feedback circuit. In euroland I have an optomix and a streams, both of which I like a lot.
Now - do I really have to pick a favorite? hope not - they’re all good.