total noob, but to me... the two "best" modules are intellijel's shapeshifter & rossum electro-music's morpheus because you can get so many crazy tones out of them and because of digital modules like those, i like the fat & nasty sound of metasonix's tube VCA.
i wonder if maybe batumi is redundant with pamela's workout. i originally had one in my play rack based on its popularity, but replaced both it AND the quad clock with it because it SEEMS like it does everything both of them can and so much more. it's programmable even, but i could see someone preferring a batumi for live use because of the sliders, but i think you can modulate pamela too, you just need an external controller. try and get an expert ruling on that.
as to the optomix, i'd mount it on the far right as i try to plan each row following the "standard signal chain"
MIDI/controller > LFO & utilities > VCO > VCF > envelop generator > mixer > VCA > effects or something similar to make it easier to visualize patches, but tend to break the sequence to group modules by brand too.
in a small rack, i'd get intellijel's polaris multi-filter. it covers a LOT of territory juicy, rubbery, vocal, chunky, & attitude. other filters might sound even juicier etc., but in all the demos i've watched, it's the analogue that covers the most tonal bases.
speaking of intellijel, their dual ADSR is my favorite envelope generator... very simple & sliders just make more sense to me.
DO NOT take anything i say as "educated". i'm just trying to teach myself this stuff, but definitely check shapeshifter & morpheus demos out to see if they sound good to you ears. they are in the "top row" of my play rack