My opinion, and it's only an opinion, and therefore worthless, is that:
OS4 - is a nice progression of AmigaOS but is still still seriously lacking, eg. support for USB 2.0
SAM - the specs are too weak for what they cost, considering the system they are trying to replace
X1000 - looks like a powerful piece of hardware, but is no more an Amiga than a PowerMac G5
MorphOS - is another nice OS but it still doesn't quite "fill the gap"
Using old PPC Mac hardware - is a good move, all things considered, but feels like an cop-out as long as it lacks OS4 support
NatAmi - should be good "classic" compatible hardware, but by now OS 3.x has been patched and hacked so much that the software may not ever be able to deliver. This is the one I'm waiting for though, and maybe AROS will make it work.
Overall: too many different projects, pulling in too many directions. AmigaOS has become Linux for the retro enthusiast. Forget KDE vs. Gnome, it's MUI vs. ReAction, PPC vs. i386, Ambient vs. Workbench etc.
I'd like to see all flavours succeed, in some kind of compatible unity, but I think I'm being overly optimistic there.