First of all, this is not my first time posting in the forum. The First time was a few months back and I had no clue what I was doing. Since then I have really taken time and become more realistic and grasped an idea of what I want my modular to do. I have read Patch and Tweak, spent a lot of hours on the forums on here and on Muff. So I am coming back into this with a lot more knowledge. But still, so much to learn.

I am looking to make a generative melodic multi layer ambient(ish) synth. I have already dived in and bought the Intellijel 7u case, Maths, Rings, quad vca, 1u headphone jack, 1u audio I/o and 1u buffered mult. These are all working along side a Mother32 and a 0-Coast. Which I am having a blast with so far.

I have a few questions from here.
First. I have bounced between the Rene 2 and the Metropolis as my sequencer. I know I can use the Mother's sequencer but honestly to me I am not a big fan of it. I know I will be using it along side another sequencer though for basic sequences. To me, the Rene 2 seems better suited for what I am trying to achieve. BUT, there are a lot of things that I love about the Metropolis. It seems a bit more user friendly then the Rene. But of course Make Noise modules are always a bit daunting at first. My question would be; which one would I be better off going with? Which one would be more rewarding?
Second. I have a lot of clock sources and not enough voices picked out in my opinion. This is part of the reason I left a big blank space. I feel like I need at least one more. But this is why I'm here. To ask for advice from people the know much more then me on the matter.
Third. I am going to be in desperate need of effects (also why I left black space) I am really looking for delay/reverb modules that are the most bang for your HP. And also, I am curious if the Polaris is a good fit as a filter for my system.

That's pretty much it. If anyone can comment and help answer my questions that would be amazing. Also, I am open to any other comments on what I have sketched out so far. Anything else that I might me missing or haven't thought of yet. Any input would be very appreciated. I am very humble and am always looking to learn more.

This is what I came up with without suggestions. I through Mixup in so I could get a stereo mixer for little HP. And ended up picking the Metropolis over the Rene and paired it with Shifty so I can sequence multiple voices. Am I making the right choice with this? Also ended up going with the Erb Verb. Am I missing anything? Anything else that would be beneficial to the synth?
Thanks. :)

Erbeverb's a good idea, yep...but I do see a problem with that Metropolis + Shifty call. For instance, you really need to have four signal sources to send the shift registers in the Shifty to, otherwise you're spending about $190 on something you won't get the full use of. And given that the Metropolis is pretty much a monophonic sequencer (albeit a very good one), that alone won't address the possible multiple voice use. Better idea: The Harvestman's Stillson Hammer mkII. This gives you four channels of easily-usable sequencing, plus per-channel quantization and a whole pile of other features for less than the cost of the Metropolis + Shifty combined. Plus, you get 8 hp back for some other use in the bargain!

Funny how you picked a very similar looking set of modules to those in my “starter” rack:
ModularGrid Rack

I can relate to your questions. I considered the EricaSynths Pico DSP as a basic effects option and would’ve added it if I didn’t have the ability to run it through my Octatrack.
I would like to add Erbeverb, Phonogene, and Rainmaker to the setup, but that’s a whole rack right there.
Since you’re going for an ambient sound, perhaps get a good reverb first, so replace the Morphagene with an Erbeverb. Not that the Morphagene is bad, but it’s a grain pitch shifting sampler, which isn’t necessarily ambient focused. I think you might want to explore some additive synth options, such as the Audiospektri HG-16. You need a delay module, too.
Regarding filters, have you considered the uJove by System 80?

What exactly are you trying to get out of your sequencer. I'm a little confused if you're looking for basic sequencing or something advanced to use along side something basic.

I'd spend a couple of days looking through manuals and watching Youtube videos around the following sequencers:
1. Eloquencer
2. 1010 Music Toolbox
3. Micro Ornaments and Crime in "Sequins" mode.
4. NerdSeq
5. Tiptop Z8000
6. Pittsburgh Modular Electronic Sequence Designer

Each of them have their strengths and weaknesses of course. You're looking around $500-700US for each except O_C ($250-300) The Pittsburgh unit is also available in a stand-alone case for $50 more; which extends the life of your rack in terms of available HP. There are plenty more solutions out there. But at the end of the day you'll do your research, hold your breath, and then hope you made the right decision as you enter your credit card info.

My opinion would be to start with something basic like the OC then make another purchase a few months later. The OC can serve quite a few purposes so it won't become redundant in your rack.