Are you baking your mac & cheese? Or attempting to replicate commercial products via the stovetop?
Personally, I prefer a baked mac & cheese to the store-bought 'noodles in a sauce' variety.
I have a couple of recipes I like, one has a southwestern flair (hot and spicy) and one is garnished with slices of fresh tomato.
If you'd like either recipe, let me know and I'll be glad to share.
Meanwhile, if you just want to try adjusting your recipe, I suggest a blend of sharp or medium cheddar, monterrey jack and perhaps swiss or mozzarella. No brie.