The Japanese one is my preferred version.
I have both the Japanese version and North America version of Sonic CD.
So long story short, I made bin/cues of both a long time ago. But for actual hardware I took the Japanese Bin/Cue and swapped the header and boot code with the North American version using a hex editor and than burnt it to a CD. The end result is that it worked! The Japanese version of the game now boots on North America hardware with no modifications. Well I could of used my Mega Everdrive X5 to boot the Japanese BIOS but I got tired of having multiple .BRM files because the cart acts like a back up RAM cart and the game makes you format those. Could of also installed a region free bios but the first method is fine enough for me.

