What's a girl to do? Well, my nature is to research everything and then decide. So, I got on the Harry Potter wiki "list of spells" and researched which one I thought would be my favorite.
Some of the others I'd use often would be: episkey, inanimatus conjurus, lumos/nox, alohamora, pack,
I'd hope to never have to use "expecto patronum" (as obviously, I hope to never be chased by a dementor), fidelus (I hope to never have a secret so big as to need that), the horcrux maker ('cause I'd never kill someone), any of the Unforgivable Curses (no explanation needed), and any of the "protego" variations.
What spell is your favorite or one that you'd use the most?