Terrain suggestions.

New terrain generation is amazing; better than most mods, but there are some things I can think of that could make it even better.

~Overworld~

-For one, rivers are still very outdated; there's nothing really special about them. They're just kind of there. I believe rivers should be reworked to function like real life rivers; forming from small streams in the mountains that slowly merge into bigger and bigger rivers as they flow downhill, eventually ending in a river delta at the ocean.

-Biomes should have a minimum size. This would prevent really small islands of one biome from forming; which is often one of the most immersion-breaking things in Minecraft for me. Coming across a desert thats only 60 blocks across just doesn't feel natural. Different biomes could have different minimum sizes as well, allowing for more fine tuning. They should also have better transitions. Seeing the dark oaks abruptly stop when it hits the plains also doesn't feel natural.

~Other dimensions~

-The nether needs to be bigger. Currently it's only 128 blocks tall; that was already behind the 256 block limit, but that problem is made even worse now that the normal height limit is 320 blocks, down to -64. I believe the nether should be expanded vertically at least to 256 blocks tall.

-The end is still very bland. Though I like the desolate feeling it gives off, it could certainly use some more features to make it a dimension worth returning to after getting elytra and shulker boxes.