It's honestly impressive how well Motorola 68000 assembly is both A) able to be manually reversed into C-like code, and B) understandable, even having never touched 68k ASM before in my life.
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I could absolutely talk your ear off about SPARC, though. It's the closest thing to a perfect set of opcodes that I've ever seen. It's light and streamlined, with an abundance of synthetic opcodes that can be constructed from a relatively small handful of real instructions.
The whole register-windowing part of the SPARC architecture was hot garbage, but the IU's instruction set, at least, was absolutely beautiful.