You know, I promised myself I'd not post my comparison of MOS vs OS4, but you know, with all of the goodwill happening on both sides, I figure it can't hurt. Understand, I do not know the inner workings of OS4, so my data is based soly on reading the featurelist and the various reports from the Friedens (ignoring Herman's statements, no offense Ben. You're a great guy, but not a coder):
Emulator: MorphOS has Trance, OS4 has Petunia.
API support: MorphOS supports AmigaOS's API + PowerUP and WarpOS. OS4 only supports AmigaOS's API.
3D support: MorphOS already has PPC native 3D from Rave3D + a Warp3D layer with a GL system (JunGL) in late development. OS4 has thus far only mentioned Warp3D + some new system called NOVA (No idea if it is GL-based or not) along with a MESA port not yet under development (as of October, last time I checked).
Desktop: MorphOS has full top-to-bottom 24/32-bit color support. OS4 has various elements still using an 8-bit pen-based system.
TCP/IP: Both systems have a native PPC stack under development. From tests, performance is very comparable.
Game support: ignoring 3D which was discussed earlier, OS4 has a more advanced interface API/driver system than MOS. In addition, OS4 lists more supported sound cards than MOS.
Included software: MorphOS's bundles many registered programs with the system (like MUI, Voyager, etc) + offers the Superbundle. OS4 includes only lists freeware or shareware versions of core applications (such as IBrowse). Pretty understandable based on each OS's development status, however. (Don't begin cutting deals for registring software till you're ready to ship)
Architectural design: MorphOS designed the core module then developed a sandbox for classic applications. OS4 developed the classic support, with future plans for the core system to be changed/evolved. I did not discuss ExecSG or any other of OS4's new capabilities in this dept, because all I can do is guesswork based on published docs, not all of which are clear at this time.
My judgement on all of this: MorphOS's list shows that it is more mature, more "ready for prime-time", but this is not a negative slam against OS4. Remember, MorphOS has been under active development for going-on 5 years, compared to OS4's 2+ years. At twice the development age, of COURSE MorphOS is more refined, more polished. This is not exactly a huge leap of logic here. I fully expect OS4 to rival MOS's current features in another 2.5 years. But imagine where MOS will be by that point.
This is just my personal viewpoint, feel free to express yours.