2 voices (3 at most) seems about right in this size case - any more and there's not enough room for the support modules that are needed to make the most of them - see my signature!
right now I'd buy beads of all the granular type modules - sooner or later they will be gone...
the quantizer looks superfluous to me - your midi->cv output(s) will be quantized already as are those from Marbles...
a decent reverb and delay will go a long way
if you want chords - either be prepared to have a really crappy way of sequencing them (you have this already in plaits) - or for it to cost a lot (especially if you want to have everything stay in key) and take up a lot more space than is free in this small case - or just get a cheapish polysynth along side the modular
more modulation (something that can go really slow - zadar for example), more utilities (especially vcas - veils is great and possibly a sample and hold), maybe a filter or 2, maybe a matrix mixer (or 2) for combining modulation sources and using as send/return for the effects etc
patching advice - send outputs to inputs - download the 'maths illustrated supplement' (if you haven't) it's a good jumping off point for Maths
"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