personally in a starter case I would rather have Marbles than Pams - I have Pams and whilst I use it a lot - I'm not a big fan of programinig it - the screen is small and at the moment it is not in an ideal position in the rack to see the screen - marbles on the other hand has a lot of knobs so is much more interactive
I really wouldn't bother with twiggs either - Pams or Marbles can do this and there is not so much in the case that you will need or want a branches-alike module let alone 2 - I have one and a DIY one in the back log - but I have about 1500hp of modules - I use the branches I have mostly for hats - as it is easy to get nice skip/open/closed ratios by self patching the top section to the bottom section
I would also consider swapping out the micro clone of plaits for a real one - there is plenty of space and ergonomics are very important - micro modules = poor ergonomics - it's possible you've never actually seen an eurorack modules in reall life yet - a lot of people in this situation get a shock with how small modules actually are - it'll cost a few extra $/€/£ but not many - and mutable support is fantastic - I had a button fail on Marbles - back to Emilie to fix - sent last Thursday - should have it back this Friday!
how are you intending to sync the modular to external gear with Pams? - there are a couple of midi expanders which may work - I use an audio pulse in the DAW (the one i use is from make noise web site) and send that through an expert sleepers es8 when I need sync and use that as clock in to Pams - in computer OSes audio is much higher priority than midi - so timing is tighter - using a midi clock via a BeatStep Pro was sloppy/out of time
as a next module - if you can find one buy kinks - it is a really useful inexpensive utility module - it's been recently discontinued - but there is still stock in some shops
otherwise I would buy plaits and then veils - plaits has a built in lpg (which is a combination vca/low pas filter) - so to a certain extent you won't need either a fillter or vca for the audio path to start with - the vcas will be useful for modulation purposes (modulate your modulation)
"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