felt like putting this here because I've been playing hardcore with this modpack for a long time and it's pretty dang fun
LIBRARIES (needed for the other mods to work!!!)
Applecore: The Spice of LifeCodeChickenLib: Just Enough Items
CoFH Core: Thermal Expansion
CoFH World: Thermal Expansion
Custom Mob Spawner: Mo'Creatures
Mantle: Tinker's Construct
RadixCore: Minecraft Comes Alive
Redstone Flux: Thermal Expansion
Thermal Foundation: Thermal Expansion
MODS ("modifications")
Construction
Mr. Crayfish's Furniture Mod: Access to craft both rustic and modern furniture. More than that, they are actually functional ! Put glasses and plates on a dining room table and sit at the chair ! Put your favourite GIF up on the telly ! My only complaint is that the tables & counters are very limited in what objects you can put on top. You can't put torches or flowerpots or anything from other mods on Crayfish surfaces, only other Crayfish items, which is pretty annoying.
Food & Survival
Pam's Harvestcraft: A variety of new plants, meats, and the methods to obtain them. There are also over a hundred ways to turn these ingredients into food from a variety of cultures, from a simple garden salad to chow mein to chicken pot pie. Works especially well with Biomes O'Plenty to add even more variety to each biome, as different plants & meats are found in different climates.
The Spice of Life: Encourages eating a variety of foods by decreasing their effectiveness the more you eat them, resetting after you've eaten 12 different foods. Food that fills more hunger (so, likely to be more complex) grows ineffective faster, so that way "snacky" foods you may craft in bulk last longer than, say, eating a dozen garlic chicken dishes in a row. By default all food still fills half a bar so any of the basic ingredients from Harvestcraft will not lose their effectiveness.
Mining & Redstone
Thermal Expansion: Industry, both mechanical and magical, allowing you to automate & innovate most processes in Minecraft. Split items into their original parts, drill into the earth, capture the souls of mobs for your own nefarious purposes, and basically anything you can do with machinery. There's so much stuff in this mod it justifies the 4 libraries needed to run it.
Tinkers Construct: Overhauls the tool system, with a variety of more types of tools (kamas and mattocks rather than hoes, three different swords, etc) along with materials, allowing you to customise tools however you'd like. Make a sword with a stone handle and cactus blade if you want, or a shovel with a steel head.
Mobs
DoggyTalents: Better tamed wolves. They can heal at dog beds, and be taught special abilities with "training treats" (such as fishing or shepherding). They also have an automatic naming system, specified sexes, custom textures, and a hunger stat.
Dragon Mounts: When you defeat the ender dragon (which I've never done in hardcore, so I can't exactly speak for this mod), you may hatch the dragon egg into a rideable companion. Again, no idea how this mod works in practice because I haven't gotten there yet, but it's compatible with everything else on this list and provides more motive to actually go to the End.
Gargoyles: Now there's a third type of utility mob: the flying gargoyles, who sit on perches and wait for hostile mobs to approach before setting upon them. It only adds this very specific mob, but they're badass enough to consider implementing this mod. There are also naturally-generated cathedral structures with hostile gargoyles that, while containing loot, should be avoided until you're strong enough to survive places like the End or Nether Fortresses, because they're just as dangerous.
Minecraft Comes Alive: Sims-ifies the villagers, giving them more diverse & human skins, personalities, relationships, and interactions beyond trading. You can befriend, date, marry, and even have kids with villagers you develop reputation with. They also have more behaviours depending on the individual, such as "guard" villagers fighting hostile mobs, and riding horses.
Mo' Creatures: A bunch of new mobs, both animals found in real life and fantasy creatures, both animalistic and humanoid, tameable or hostile. Sometimes it can be a bit buggy but in my opinion it's worth it for the diversity it offers. It's not just obvious animals, either-- there are plenty of insects and small animals that provide little other than ambience, but it works really well with Biomes O'Plenty in my opinion. Also, pet snakes !!!
UI
Just Enough Items: A no-brainer for any modpack, as it lets you quickly view recipes & uses for items from other mods. Crafting purists may call it cheating, but I'd like to see you get anywhere guessing at crafting recipes from a dozen different mods.
World Generation
Additional Structures: Naturally-generated structures from small, naturally occurring objects to spice up the landscape (such as dead trees and boulders) to man-made ruins (such as temples, wells, and abandoned farms). Doesn't impact much more than simple ambience, though of course the man-made structures can provide materials you may have had trouble finding otherwise.
Biomes O'Plenty: More variety to biomes along with selecting continent & archipelago options at start. more trees, wildlife, and objects such as decorative terrariums and biome-exclusive minerals.