Great course from King Unique, as usual. He makes learning fun and easy.
One thing I would be interested in FM, Additive and Subtractive synthesis, is a course (or one for each) on recreating natural instruments. I think that would give me a good foundation creating original sounds as I would have a better understanding of how to achieve certain types of timbres that I might want to start from, or add to; focusing on breaking a sound down into components, and waveforms, envelopes and harmonics. It's great to fiddle and discover new sounds, but it can also be time-wasting figuring out an idea you already have in your head if you have little idea where to start.
ie. sines are good for bass, odd harmonics are good for bells, even harmonics for organs, do you want it breathy like a flute, bowy like a violin, brassy... I got a little bit of that. I want more