I haven't played Exapunks, so I can't say, but about AT&T vs Intel: maybe the order of "mov source, destination" and "sub subtrahend, minuend" is easier, since

I haven't played Exapunks, so I can't say, but about AT&T vs Intel: maybe the order of "mov source, destination" and "sub subtrahend, minuend" is easier, since it lines up with English phrases like "move this into that" and "subtract this number from that number," but everything else about Intel syntax was easier for me when I first learned assembly.