Heck, 1.7 is STILL one of the most popular versions for the modded scene, and it came out in 2014 (because it was an unusually long gap between updates, as was 1.8 which a lot of mods didn't bother updating to due to not much being added to the base game).
1.7 has RTG [1], can be worth a try. I always enjoyed the RTG worlds, but now I am mostly playing skyblock(-ish) packs, so I do not really care about terrain anymore.
Oh, I thought RTG was all about removing floating islands and making the mountains more mountainous. I didn't realize it also made the huge cave systems you get with 1.18.
