What would be a strong and useful main four be?

Main four as in main four spells, the first on hand when encountering enemies that can easily no sweat knock em out. I’ve been deep exploring, like screw doing any quests right now if anything I’m flying around and finding as many available sides without starting or even talking to them (so no they’re not in my log yet) but I’m constantly fining group of spiders and poachers and have winded up in some named enemy camps (please tell me I’m not jumping ahead by attacking them I’ve defeated a bunch already) as well as sooooooo many trolls like, omg I’m going crazy and I’m ngl once I’ve got avada kedarva trolls won’t be a bother to me but still. I’m gonna be doing another day of just exploring around and once I’m satisfied I’ll go back to actually playing 😂 My current main four are glacius, confringo, difindo, and diffindo. I’m thinking about switch glacius for expeliarmus but I’m unsure. I’d like to be snoopy and hear what everyone else has for theirs and how it helps them!