I am using both MorphOS2.1 on Pegasos1 and AmigaOS4.1 on A1XE at the moment.
My personal opinion is that MorphOS is more advanced in almost all areas now. MorphOS is more mature and finished production, while OS4.1 needs developing on many areas still.
The most noticeable problem with OS4.1 is the lack of the features in Workbench and especially with the file handling. Roughly said WB is pretty much on same level than on 3.9, while MorphOS's Ambient has developed a LOT. Ambient has lots of features copied from Magellan2 and most users don't even need any external filemanager anymore. On OS4.1 you have to rely on old time two view filemanagers like Dopus4, which isn't comfortable at all for me anymore, as I've used more advanced filemanagers on classic Amigas over ten years.
I also find the OS4.1's oldskool prefs system pretty messy nowadays, when there is much more settings needed than 20 years ago. MorphOS has them more clearly organized and rearranged. OS4.1's prefs also don't feel consistent.. it feels like they've taken prefs from old programs from here and there and haven't adapted them with any plan.
MUI4 is a big advantage for MorphOS. I've always like MUI's way to have power for configuration on user. MUI4 has gotten a lot better than MUI3.x was. It also gives consistency to system and programs as MUI got as de facto standard on Amiga and for example most networking programs use it. Now you can tune whole system with it.
MorphOS's shell is much more advanced than OS4.1's. In OS4.1 you don't have even scrollbar or backbuffer etc, but in MorphOS you have those and even search options for buffer, multiple tabs on one shell, session saving, terminal emulations for ssh use etc etc.
Poseidon4 on MorphOS is also great USB stack. It's feature rich and supports USB2 speeds etc. On OS4.1 I've had some weirdness with USB. With several devices it seems to work bit unreliable. It also is very slow mounting big mass storage devices.. takes almost minute before there comes icon on workbench with my external HD. On MorphOS that's instant. OS4.1 also supports USB1.1 speeds only.
Filetype system is also great on MorphOS, you can define lots of actions for each file type (mimetype). What happens when you doubleclick file, drag&drop file, click it with RMB etc. You can have several different commands for each action. Filetypes are also arranged hierarchly and they inherit the options to lower levels. You can for example make certain actions happen for all pictures and then more exact options for each individual picture format. On OS4.1 you only can edit icon's default tool for each file type.
One nice touch in MorphOS is the "open" command, you can open files from shell with it. It looks operations from Ambient's mimetype settings and uses them to open files. For example "open test.avi" plays movie like it's configured in mimetypes, you don't have to remember what program or options would be needed for that file type.
Then there's lots of small details, like screen title bar modules in MorphOS. You can have things like date, cpu monitor, volume control, network indicators, info from music player etc in screen titlebar.. and the best thing is that it shows up in all screens! Not just on desktop screen. So if you have browser in separate screen, you can see and use all those things on it without need to open Ambient screen.
Amidock on OS4.1 is more versatile than Panels in MorphOS. Amidock can take all kinds of dockies like clock, cpu monitor, lenses etc, but personally I don't like dock kind of things. I'll rather have those kind of apps in MorphOS's screenbar module way.
Overall look and eyecandy is also better in MorphOS. There's cool themes for windows, about 30 different screenblankers (even 3D accelerated demoscene effects), nice background pictures and other gfx, colorful png mouse pointers etc. They really should think these things with OS4 too.. now there's ugly yellowish backgrounds with weird purple scrollbar backgrounds as default theme.
OS installation also tells about finishing touches. MorphOS installer is good looking with only some main points covered. After installation everything is ready in first boot. On OS4.1 there's lots of useless requesters telling what's going to happen next, but then at the end nobody tells if the installation was finished
There also opens some external windows, which shouldn't be visible to users IMHO. Installation is divided in two phases and there's reboot needed in between. Also some default settings are bad. For example AHI settings had defaulted to mute, no channels, 0 frequency.
I also like MorphOS's IControl prefs. You can define hotkeys for all kind of actions. For example window handling options are good. You can define mouse/keyboard actions to bring windows to front, send them to back, center them, maximize them, activate prev/next etc. You also can do certain things for whole window families. For example bring to front all open windows of certain application. In OS4.1 they're handled with traditional commodities and by default there isn't many.. basically it's old ClickToFront commodity.
OS4 has nice soft reboot, which is fast. MorphOS takes little longer to boot because it does the open firmware stuff in each reboot.
3D support or WOS emulation in OS4 seems to be unfinished. All old Amiga's 3D/PPC games and demos I've tried had problems under OS4.1 while they worked on MorphOS.
Old OS friendly apps seem to work pretty fine under both systems. Some work better under OS4 and some under MorphOS. But OS4.1 feels to be more crashy when they don't work correctly. Worst thing is that filemanagers seem to suffer under OS4.1. But some wordprocessing etc big apps work fine under 4.1, some even better than on MorphOS.
I must say I am bit disappointed on 4.1... especially after getting MorphOS in such fine condition with 2.x releases. And when it's selling as completely new product and not an update to 4.0. But if there wouldn't be MorphOS I surely would be tinkering with OS4 more
Although filemanagement area should be much more advanced to be able have it as my main platform... I really hope it will get better and more mature product, but there is work to do still.
