VCAs - if you can find a new veils - then get that it's smaller and does the same job as the intellijel - and for less money - slightly different spec - but you seem to already have a tangle quartet - so I would just stick with that for now
Wavefolders - there are lots of them from low cost to high cost - I use a lot of the Doepfer ones for video - they work great
Quantizers - if you are using a sequencer, the chances are it is already quantized - so you probably don't need an separate quantizer, as Nick explained they are useful if you are generating the v/oct using lfos etc - when you have a lot of voices (I have 11 + percussion) you might find you need/want to make sure everything is in tune with each other (multiple sequencers and vcos) in which case a 'biq' quantizer can be useful - I have a sinfonion, which I find useful - not that you need anything as powerful as this now!
quantizers won't so much tame you vcos, as send them v/oct that is in scale - the vcos still need to be tuned so they are actually in tune with each other - you can either do this by ear - or just use a tuner - pedal or app for instance - the more vcos/voices you have the better
taming your vcos is probably better done with filters
"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