Good question; I believe I can help a little.
I have “all” the foogers - one of each model at least. Here’s what I do and plan to do with them, and how I do it:
101 Filter: use it for tones, drones and animation. I fiddle with it a lot, but not the most - both cv connections and knob tweaks. I tend not to plug an expression pedal into it directly, it would usually get fed via CP-251 or another fooger, but when it is on I may manipulate it manually a little.
102 Ring Mod: use it for everything. I definitely tweak it the most, and change it’s set-ups the most. I use it for tremolo, tone modifying, vibrato, ring modding… It is my go to fooger, however the others support it quite a bit - via envelope controls, lfo’s, ocsillators etc. Use and expression pedal on it and manual tuning during playing regularly. It is the most instrument like of the foogers IMO.
103 Phaser: Love it, but don’t use it so much. More of a production tool than an on the fly foundational player tool.
104 Delay: Use it the most by far. Sits in my amps FX loop, and get’s tweaked via two expression pedals on the fly regularly. Don’t play the knobs too much… I plan to mix and match the fx loop within it quite a bit, but I just haven’t gotten there yet.
105 MuRF: Going to upgrade to MIDI, have the guitar version. I love it, just like the phaser. It has more live use than the phaser, but just haven’t found it’s applications yet, but it is getting more and more attention lately - thus the upgrade. I play guitar, bass and keys, and MID program drum loops, so the upgrade makes sense.
107 FreqBox: Love to hate this thing relationship. It has uses I’m sure, just not sure what they are yet, since I have other favorites that do similar - not exact things. If I ever sold a fooger this would be it, but only because I haven’t found it’s purpose in my current perspective. Still fun to mess with though!!! Great as the carrier for the ring mod.