Congratulations, you all avoided actual horror and instead only got mild horror! Time to reveal the options, in ascending order of rank.
4TH PLACE (6%): eZ80
It's the Z80! But with an expanded 16MB address space that doesn't require any cursed bank switching! It extends a bunch of register pairs to become register trios for the 24-bit address bus. It's generally only available in microcontroller-y form, but this provides a buttload of bonus peripherals (including serial ports, as well as built-in flash ROM and RAM) which would have simplified development. Though, this option would have made it directly compete with the Agon line of homebrew microcomputers, which use the same CPU. It's been done before, but still a fun choice.