Love these:
  1.18 Applied Energistics 2  | Store your items in a computer
  1.16 ChickenChunks          | Keep chunks loaded when you're logged out
  1.16 CoFH (see bottom)      | Automation, energy generation/storage, so much
  1.12 Dimensional Doors      | Place a door to create a portal
  1.16 Draconic Evolution     | Super end-game OP equipment and bosses
  1.12 Enchanting Plus        | Choose the enchantment you want
  1.16 Ender Storage          | Chests and tanks with linked inventories
  1.12 Extra Utilities 2      | Lots of random things, all awesome
  1.18 Extreme Reactors       | Nuclear power generation
  1.16 Industrial Foregoing   | Automation, also Laser Drill
    Integration Foregoing     | Integrates IF with other mods
  1.18 Iron Chests            | Chests with larger inventories
  1.16 Psi                    | Program actions into a special tool
  1.18 Tinkers' Construct     | Customizable tools and weapons
  1.12 Tomb Many Graves       | Keeps your items in a grave if you die

Love these (client-side):
  1.16 HWYLA                  | Tooltips (Here's What You're Looking At)
  1.16 Inventory Tweaks       | Inventory sorting and keyboard shortcuts
  1.18 JourneyMap             | Map + waypoints
  1.18 Just Enough Items      | Search items and explore recipes

Love these (server-side):
  ?.?? Backup mod (I don't have a specific one; just pick one)
  1.18 Just Enough Resources  | Server performance and profiling
  1.16 Morpheus               | Sleeping requires fewer people
  1.12 TickProfiler           | Server performance and profiling

Also cool:
  1.18 Bad Wither No Cookie - Reloaded  | Mute global sounds
  1.12 Baubles                          | Extra inventory slots
  1.18 BuildingGadgets                  | Building automation
  1.16 CB Multipart                     | Cut blocks into smaller pieces
  1.16 Chisel                           | Tons and tons of decorations
  1.16 Classic Combat                   | Reverts combat to pre-12
  1.12 ComputerCraft                    | Program computers and robots
  1.18 Cooking for Blockheads           | Kitchen appliances and recipes
  1.18 CraftTweaker                     | Add custom recipes
  1.18 Discord Integration              | Link chat to a discord server
  1.16 Duplicate Entity UUID Fix        | Fixes a dumb bug that spams logs
  1.16 Dynamic Trees                    | Chop down entire tree at once
    Dynamic Trees Extra Utilities 2     | Mod integration
    Dynamic Trees Pam's HarvestCraft    | Mod integration
    Dynamic Trees Quark                 | Mod integration
    Dynamic Trees Tinker's Construct    | Mod integration
  1.12 Ender IO                         | Strange tech mod with horror themes
  1.16 Flux Networks                    | Wireless power transfer
  1.12 Galacticraft                     | Go to the moon
    Galacticraft Planets                | Also Mars and Venus
  1.18 Immersive Engineering            | Very aesthetic machines
  1.18 JAOPCA                           | Inter-mod ore compatibility
  1.16 Mekanism                         | End-game automation, complex recipes
    Mekanism Generators                 | Power production for Mekanism
  1.12 Netherending Ores                | Generate overworld ores in the nether
  1.12 Pam's HarvestCraft               | Many, many, many more plants and food
  1.18 Quark                            | Quality of life improvements
  1.12 Realistic Terrain Generation     | Modifies terrain generation slightly
  1.16 Woot                             | Automated mob farming with spawning

CoFH Plugins (1.12):
  1.12 CoFH Core
  1.12 CoFH World
  1.12 Redstone Arsenal
  1.12 Redstone Flux
  1.12 Thermal Foundation
  1.12 Thermal Expansion
  1.12 Thermal Dynamics
  1.12 Thermal Innovation

CoFH Plugins (1.16):
  1.16 Archer's Paradox
  1.16 CoFH Core
  1.16 Ensorcellation
  1.16 Thermal Foundation
  1.16 Thermal Expansion
  1.16 Thermal Cultivation
  1.16 Thermal Innovation
  1.16 Thermal Locomotion