The ISA doesn't really matter (at least, not between MIPS, ARMv8, and RISC-V) when you're first diving into computer organisation. That's why one book can be sold with three different ISAs. The overarching concepts are mostly the same: you have digital logic, IEEE-754, basic assembly (add, sub, and, not, xor, load, store, shift), pipelining and hazards, caches.
Only afterwards do the differences between the ISAs come to play, when you have complex vector and ISA-specific instructions, superscalar pipelines, atomic instructions, etc.
I am more inclined for ARM version since that's applicable to both all current Apple hardware and school Chromebooks.