It is not the boards themselves but the interface for coding those boards I bring forth here.
I am testing Arduino compiler modifications on my printer, is a mess.
I have learned that Duet boards are handled through RepRap Firmware, unlike the Marlin runing on Arduino, although the Duet started as Arduino clones not so many years ago and the RRF is build upon Marlin.
So unlike Raspberry PI, the above two are cousins.
Please come forth and explain why you think one is better than the other, or at least why is it working better for you.