Just ordered my first modules. Recos?

I'm very new to modular synthesis. I currently own a DSI Prophet '08, original Roland JX3P, Behringer Model D, Ensoniq TS12 and several Akai and Roland samplers. I create HipHop, IDM, Ambient, OST, VGM, Dungeon Synth and occasionally synthwave or house. I first placed the Behringer system 100 modules in a basket and cancelled the order after notification everything was on back order. I decided to start with these.
The tiptop audio happy endings racks will be most useful for me since my studio room is already cramped. I have an Omnirax Force 36 desk (https://www.wwbw.com/Omnirax-Force-36-Workstation-548085-548085000203000.wwbw?source=TWWR5J1BB&cntry=us¤cy=usd) and the right side monitor stand/rack bay is cleared and ready to install two of the racks which are on the way. One of them comes has the power module. So far, I've ordered a Pittsburgh SV1-b, Noise Engineering Mimetic Digitalis and a Erica Synths Black Hole DSP 1.
I want to sequence the sv1b and the model D (staying in it's own box) for normal synth patterns and create long ambient sounds maybe get a little crazy with noises. I can stand to afford one more module for my first crack at this. Any recommendations? I thought about getting a Serpens Modular Hydrus but I have yet to see a video or demo of it. The description sounds like something I would utilize but not totally sure and I'm trying to fight my low level OCD of completing that 8 HP left in the first rack. The second rack will be in the closet ready for expansion once I feel confident enough creatively and financially to grow.

EDITED Dec 28th 2020, 12:43

You've severely limited yourself here. This build is too small to support something like the SV-1 without making serious compromises to other subsystems that should go in here. A far smarter mover would've been to study the SV-1, then obtain the "primitives" behind its panel as discrete modules. As it is, your rig here is now being "forced" in terms of operating capabilities by that one module. This actually negates the point of modular...YOU should determine how things function, not some particular module.

Also...why do this sort of setup in general? 2 x 84 is pretty limiting as well. I note that you've got a uZeus in there...so why not jettison it AND the 2 x 84 and go with a Tiptop Mantis? You'd have 40 more hp to work with, the rack is prepowered so no need for the on-panel supply, and it has proper filtered power bussing...no flying busboards! But even if you go with that (IF you can change your order ASAP!), the SV-1 is still a no-no, as even 2 x 104 is too small for a big honker like that.

You would be wise to listen to Lugia... If you absolutely have to fill out that 8hp check out Pamela's New Workout. Every rack benefits from PNW. Or a Disting EX

As a beginner as well to modular, my advice is to buy the largest case you can buy, the bigger the better. I recommend a 9u or 12u case at the bare minimum. That way you won't be squeezing tiny 2hp modules in it. Thus far, I really like the MDLR 12u and 14u mobile cases they have 1u rows of tiles so you can add the Intellijel utilities to those and save the space for larger cool modules. Pamela's New Workout is great. I have mixed views on the Disting- lot of menu diving and not the easiest to use for live performance or beginners.

Thank you very much for the help! I can tell this will be a different experience compared to any instrument I've used. The trial and error of it all is exciting surprisingly. I do not anticipate creating a "perfect" setup I notice many noobs like myself attempt. I know this thing will grow. Back to the scratch pad lol!

Hey, don't sweat it...NOBODY gets first builds right. Or the second. Or ninth. And so on. My suggestions would be to...

1) Study what's on the site. Not just the modules, but also look at builds done by experienced synthesists.

2) If you haven't got a copy of VCV Rack, get one. It's free, for one thing...and although it's a bit of a processing hog, it gives you a much clearer idea of what you need to build because it is, after all, a Eurorack simulator. It even has a number of "ports" of various Eurorack hardware modules.

3) Build. Tear down. Build. Tear down. Build. And so on. Think of this as pretty much the modular synth builders' version of using a practice room to work out a musical piece...only, the piece is quite physical as opposed to the usual dotz-n-linez. But like time spent in a practice room, you're honing something into a state where its perfect FOR YOU.

Takes time. Hell, I've been working with electronics in music since the late 1970s, and I'm STILL running into totally new ideas on here.