RISC-V is the new hotness but it has limited usefulness in general purpose osdev at the moment due to slower chips (for now) and the fact not a lot of ready-to-go boards use them. I definitely think that's changing and I plan to target RISC-V; I have just always had an x86 machine, and I have built some electronics that use aarch64, so I went with those to start.

Kernel is still in early stages but progress is steady - it's "quietly public". https://github.com/oro-os