We're officially the TPR cheesesteak thread now. And now I want one, so thanks.
Dalessandros is super good, one of my absolute faves (its a HUGE sandwich!!! you've been warned!) but be aware its tucked up into a neighborhood northwest of center city/touristy stuff I that assume you'll be doing here? Its not teeeeerrrrribly
far but if time is of the essence dont go during peak times like say Friday or Saturday night. Traffic can be bad and there can be a line around the corner. I also wouldn't go there and expect to sit in there and eat. Its small and usually packed. But you'll definitely get the real Philly experience there. Also good about Dalessandros is Chubbys (their "rival") is right across the street and they're not bad either. Some friends like them better. So if one place is mobbed you have another respectable option. A little more on that: https://www.phillymag.com/foobooz/2014/01/21/cheesesteak-rivalry-dalesandros-versus-chubbys/
If you're going to be in town (or "Center City") Campos is good - where I sent Bill and Brit and Andrew. Easy to get to and again if you're not there during peak times you can get a table (indoor or out) and its a nice little spot to hang and people watch. Johns Roast Pork might be the best, or one of the best - but its a little drive/Uber ride from in Center City. Its a completely unassuming small roadside shack near the Delaware River and a bunch of big box Target/Ikea type stores. Its but easily one of the best steaks in Philly. But if you go there also get a roast pork sandwich with long hots and provolone. Sweet lord.
Philly is a city of neighborhoods and they all have their good cheesesteak place - Fishtown has Joe's, Northern Liberties has DelRossi. Old City has Campos and Sonnys. Roxborough/East Falls has Dalessandros and Chubbys. You could go down South Philly for Johns, Tony Lukes, Cosmis or Phillips. They're all good, just don't go to Pats/Genos/Jims or Ishkabibbles (ok you can go there for fries and a Gremlin... but just don't even go to South Street. Its awful).
As far as toppings, its funny with all this talk, I'm realizing I don't really eat cheesesteaks all that much anymore but I do get crazy intense cravings for them sometimes. When I do its just some salt and pepper. I'm a wiz (or provolone) wit guy. I used to always put ketchup on my steaks growing up but I try not to each that sh*t anymore.