The best meat to use for a Philly cheesesteak is thinly sliced ribeye steak. Ribeye is the go-to meat choice for a classic Philly cheesesteak because the marbling of ribeye creates a tender, easy-to-bite sandwich. However, some people use other cuts of beef such as top sirloin, top/eye of round, flank steak, or skirt steak. These cuts tend to be a little less marbled and slightly tougher than ribeye, but they can still be used to make a delicious cheesesteak. If using a leaner cut of meat, it is recommended to add some beef tallow, ghee, or some other fat source to the meat to make it as "meaty" tasting and moist as possible.