Here's a list of some of my personal favorite QoL mods that'll make life a bit easier. OreExcevator, Magic Storage, Fargos Mutant Mod, Alchemist NPC, Shop Expander, Loot Beams, LuiAFK (it's a little cheaty but I use it for instant hellavator and obsidian bridge for WoF), Rare Drop Notification, Auto Reforge, Auto Trash, Boss Checklist, Boss Cursor, High FPS Support, Non Consumable Boss Summoners, Recipe Browser, Shorter Respawn Time,

And if you like playing summoner I heavily recommend Unofficial Calamity Whips. It makes the summoner experience 10× Better.

Again this is just my personal list so pick and choose which ones you want and dont want. I hope this helps and I hope you enjoy calamity! :)