https://www.curseforge.com/minecraft/mc-mods/better-badlands
https://www.curseforge.com/minecraft/mc-mods/bayou-blues
https://www.curseforge.com/minecraft/mc-mods/abundance

Mod description
These 3 mods add new biomes that pair beautifully with the BYG biomes and add more variety to the existing vanilla biomes.

Why would you like the mod added?
I think these mods would add more life and more decoration types for E6 and i really think they have some potential to be in the pack.

We'll investigate Bayou Blues & Abundance along with Environmental when we move closer to 0.5.0 :) Moved this suggestion to #1571

Edit: Better Badlands was suggested previously and was decided against.