To be qualified as being AmigaOS-like or maybe just inspired is very much dependent on the Eye of the Beholder. Some think only MorphOS (in combination with the ABOX environment) and AROS qualify as such, others would include BeOS (and clones), AtheOS, intent and many others on the list as well.
Well, AROS is AmigaOS like, becuae it is a clone, right down to the smallest sub system... It works just like AmigaOS 3.1 works. Thus if you run it on a real Amiga, Amiga software won't know that it's not running on AmigaOS 3.1...
BeOS, AtheOS.. etc... are Amiga inspired, but they don't work like AmigaOS 3.1 works.
MOS is clever... and is different to all of the above... it's a bit like two OS's running together... hmmm, that's a bad description... nevermind, you get the idea.