I’m not sure what your budget is, but if you could swing it, I might suggest you consider the following. Buy one poly synth to serve your needs as described in your OP. I’d agree that the Deepmind 12 would be a good choice. Consider also getting a used Arturia MicroBrute. It is in my opinion, one of the best analog mono synths around for learning the basics of subtractive synthesis. It’s inexpensive, sounds quite good, and doesn’t have a lot of bells and whistles. All of which makes it a terrific platform for learning. Couple those two synths with a Syntorial subscription, and I’d say you’d be on a great path toward progress.