Which would be a better replacement for BIOS/uefi ? Coreboot or Libreboot ?

First check if your machine is compatible with either. It's probably not.

Ahem, what's a better replacement for pepperoni on pizza? Ham or tuna?

I guess it depends? What are you going to do with it? And what do you like? What's the rest of the ingredients and does that fit?

Can you give some context?

Another multy poster or bot ,block him