I tried Lithosphere, and then I learned about a generator built on top of it by the same developer named "Still Life". I prefer both of them over JJThunder.
JJThunder is impressive due to the sheer size of everything, but that's really it. It's all a wavy landscape with a shitload of generic biome elements spammed over a big area. It's boring.
Lithosphere and Still Life aren't nearly as big, but they still are way bigger than stock Minecraft. What they bring to the table which JJThunder doesn't is variation with new biomes and intermediate biomes to transition between them. It never gets boring and it looks amazing, too! I don't think I can ever go back to playing without these.
Volpeon