Annie's Shells and White Cheddar rule them all - https://www.annies.com/products/pastas/shells-white-cheddar
I made cauliflower Mac and cheese tonight and it was better than both. I'm back on a low carb diet. Fight me.
Making mac and cheese from scratch is possibly the easiest, least-****-uppable thing you can do. Unless you can burn boiling water, at that point you're on your own.