You may substitute plain Greek yogurt for sour cream as desired. Using different cheeses (grated vs shredded vs shaved) will bring more texture and different melting consistencies to the dip for a multi-level feel. Our cheeses of choice are shredded mozzarella, shaved parmesan cheese, grated pecorino romano cheese, and cream cheese. I would recommend fresh blocks of cheese over store-bought pre-shredded cheese to avoid a grainy texture.