fx aid does way more than a cathedral... there's 100ish algorithms to choose from - remember to save the pdf of what you've chosen and print it or keep it open on your computer/tablet/phone for easy reference... I updated mine and lost the pdf... so flying blind at the moment!
Modulation and utilities...
modulation:
Stages is great - grab one whilst you can (will be discontinued soon)
Batumi/nin & Zadar/poti are very good
Chaos is useful so something like the nonlinear circuits triple sloth
Random is also very useful - there are lots of random/noise sources out there
A great technique is to mix your modulations together - I like a matrix mixer for this... I;ve got a couple of smaller DIY ones, but if I was doing it again I'd go for a doepfer (or 2) and maybe a 4ms vcam... may do this in the future - either upgrade or add
utiltiies:
sequential switches - the cheap doepfer one is great
mixers of all sorts - matrix and various sorts of unity mixer, with or without voltage control, I tend towards dc-coupled ones as they can be used with modulation as well as audio, but something based on the moog cp3 might work well for you with the semis as it can add a bit of grit...
logic: you've already got a bit in maths, but the joranalogue compare 2 adds another interesting take - many more logic functions and works around windows (so you can set the comparable ranges of the signals, which is a useful feature)
rectification: always useful - I used to recommend the mutable instruments kinks module (as it had this and logic and smaple and hold) but it's been discontinued - there may be stock left, used ones available and there is a clone version - really handy
wmd/ssf toolbox is also really handy - lots of utilitiy functions in a small space (again I think discontinued, but available in stores still)
attenuators/attenuverters/offsets - these are so useful for reducing/inverting and shifting modulation signals around - happy nerding 3*mia would be my first choice these days - but happy nerding is based in the ukraine so no idea on availability
vcas - not just for audio - use them for modulation too
precision adders - want to transpose a sequence - use a precision adder - there are multi channel ones available
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities