I'm with Casey and Big Mike. Ribeye shaved thin, provolone, a good roll, grilled onions, sometimes green peppers as well and mushrooms for me. Not a fan of the Pat's, Genos version and I don't eat cheese whiz on anything, ever.
Amarosa rolls are the original but as was mentioned expensive. If you don't have access to a slicer a good alternative is to get a good quality rare roast beef sliced thin at the deli. Chop it up and grill it on a flat top or grill pan with the veggies and when it's just about ready place your bun on top to steam, load evrything on and top with provalone and your good to go. I've done this numerous times and my guests love em. This is how they do them at Publix around here and although it might not be a true Philly style cheesesteak it's damn good.
18.5 WSM 18.5 Jack Daniels OTS Weber Genesis