I prefer OpenBIOS, EFI was created by Intel with the evil intentions of removing the control you have over you own computer and giving it Windows or OSX (or any other closed source OS).
Sure, that's OpenFirmware - I don't care - just don't look at old PC BIOS.
Booting from CD/DVD/USB sound nice until you ask yourself, what I am goint to boot besides Workbench/Wanderer?
I don't see the relevance, the point is that you have to boot from something, and with custom kickstart you can decide for yourself what that something can be.
Linux and any other OS is dog slow and AROS is getting access to the same apps available in linux. ATM I cannot think of any other OS that would be available to boot in a classic amiga, so why bother.
None of that made any sense to me.