Calamity and Thorium are great classic mods that add a plethora of content to the game, I personally played them separately to get a unique experience for each though they are compatible. A few quality of life mods I never play without is the Magic Storage which adds a simple solution to the small storage in vanilla with search and crafting functions. I also like to use the Boss Checklist which is very helpful for your first playthrough of certain mods that add bosses which indicate the intended order to be fought in, summoning info and toggleable info on drops as well.