Hello @melero,
Here is an example of a rack that sort of hybridizes what @JimHowell1970 suggested and what you originally presented, as I'm guessing those were modules that are appealing to you.
I did swap out some modules that I thought might be better options, in my opinion: MIDI Thing -> Mutant Brain, Quadra and expander -> Quadrax and expander (Quadra is out of production), Magneto -> Sealegs (again, just an opinion, but I think Sealegs will be more interesting and friendly, especially when starting out). I also added a Mix 3 (to mix Shapshifter's waveforms before going into the filter), and an Out V3 (not everyone thinks an "output" module is necessary, but I do like them personally, and the headphone out and cue option is nice too). I think this build will give you an interesting and fun synth voice to really delve deep into for a long time.
You could, of course, strip things back more at first to make the setup simpler and/or less expensive. For example, take out the Quadrax and expander, take out the Mutant Brain if MIDI connectivity isn't an absolute must have, swap out Shapeshifter, Evolution, and Sealegs for less expensive/simpler options, like the excellent ones Jim suggested in his post.
I hope some of that is helpful!
