Hi and welcome,
I highly recommend that you buy a copy of the book Patch and Tweak, read it and download a free software called VCVRack on your computer before you buy anything. That will save you hours of frustration, time and money. Thank me later :-)
Also, since you seem unsure on the complex oscillator choice, perhaps watch videos on these different oscillators on YouTube? DPO is quite different from Piston Honda and so forth. Also since you are brand new to modular, you might want to instead get a basic oscillator VCO module and VCF filter module. That gives you more control and a better understanding of how oscillators and filters work.