Having recently tried pretty much all the roms out there I would summarise them like so:
Cacko rom: still has quite a few bugs, doesn't run as fast as I was expecting and installer package has serious issues. Very pretty and shows real promise - I'll probably try it again after a few more revisions :-) But locked up - a lot, and after flashing the rom 5 times in 2 days decided to give up on it.
tkc rom - couldn't get it to boot. Download only had 2 files - all the rest had 3 - so maybe something missing ?
pdaxrom - prepare to be amazed. appears to be full linux desktop implementation, complete with proper mouse cursor and all the stuff I find awkward about linux :-) Want to impress linux users - load this. Seriously it's by far the most original and impressive of the roms - but bear in mind you zaurus won't be a just a pda any more :-)
open zaurus rom - just seems a little spartan and was the only one my little pink origo card wouldn't run out of the box on. had to modify the wlan-ng.conf file. maybe a sign it's based on earlier kernel ? Just seemed to offer less than the others - I admit I didn't give it much time :-) Oh yeah no built in web browser - definitely a minus.
Original sharp rom converted to english and nand-restored from trisoft.de link - pretty much exactly what i ws expecting. A faster more versatile version of my 5500 3.10 rom. everything works, no lockups, no japanese menus, installer package so far 100%. Boring icons :-)
It's reliable, stable and not terribly exciting. But it wil do what it says on the box (assuming you can read japanese)
I wanted my c860 for serious word processing and some web browsing and possibly image playing with. And that's exactly what it's now doing. Even got interstellar flames to run :-) Only drawback is that I'll have to go back to outlook for calendar on my desktops.
The rom you settle on will probably depend on what you want the zaurus to do. Looking for linux in your pocket go for pdaxrom, want the world's best pda go for the converted sharp rom. Add individuality with oz and cacko. But whatever you go for make sure you impress the hell out of everybody you know by showing them a hi-res photo on your cg-silicon screen :-)
If you are still unsure of how to flash/restore bung me an email as It's all still pretty fresh and I've got all the links bookmarked and the files downloaded :-)