Originally Posted by jPV
I'd say that AROS is the most distant relative to the old AmigaOS, because it's not a binary compatible and many other parts are totally rewritten.
I think that needs a lot of clarifying for anyone new to AROS.
The only difference is that AROS on x86 lacks a transparent 680x0 emulator so 68k apps need to be recompiled to run. AROS on 68k is binary-compatible and in fact is the only one that runs on a classic Amiga without a PPC accelerator. AROS is no more rewritten than MorphOS - they're both clean-room implementations. Even OS4 has many rewritten pieces.
This is not to criticise any other platform or say "AROS is best" but I don't think it's fair to call it the most distant relative.