Hexterra offers a beautiful world generation with Dynamic Trees and various biome mods. The core mod, as the name already tells, is Hex Lands which spices things up alot since you can find biomes quite quick and it's just a whole new experience. The newest version of Hexterra includes more than 200 mods which are in my opinion all nice and sweet and also do not make it too full since a lot of them are utility mods.
Of course tech and magic mods like EnderIO, Draconic Evolution, Refined Storage and Applied Energistics 2 for mass item storage, Mekanism, Thaumcraft and Psi are also included.
Hexterra also offers a lot of dungeon gameplay via Roguelike Dungeons and BattleTowers. Scaling Health makes the mobs more tanky each time you kill something so it never gets too easy.
Many new mobs come alongside these many mods with modifications like Exotic Birds, EnderIO Zoo and many more.
You can find all the Changelogs here: https://pastebin.com/9i6Bte7x.
I highly recommend installing Optifine for the dynamic lights and the performance boost [https://optifine.net/home] and allocating at least 6.5 GB of RAM.
Currently it looks like you have to include Optifine because otherwise the modpack will not start.
If there's any major issue crashing the game feel free to dm me or comment below.