I said x86, but I guess I already have that and way better performance than any actual "Amiga" machine with any cheap i5 or i7 machine I come across and throw AmiKit on.
There is absolutely no software available only for OS4 machines that makes them worth the price of entry, I believe I'd be embittered if I spent that kind of money on such a machine and found it less capable than my cellphone. However, if I could run the newest OS (and yes, seamless 68k would be required for consideration) on the machine on my desk right now I'd definitely consider it.
Sorry for the bluntness, but I've (finally) gotten to the point where I feel computers should "just work" and nothing about NG Amiga machines (or the OS) give me the impression they can.
