Piper's Pub keeps getting better and better each time I visit.
First is the beer selection. They do a great job. The balance is excellent. Some places always seem to be IPA heavy or Stout heavy, Piper's always maintains a healthy balance.
The food is my favorite part though. They've recently started baking their own bread, including for their sandwiches. Their Pittsburgh salads use good steak. Their pub burger is my favorite burger in the city.
If you want Boxty or Guinness Stew, this is the place to be. Both are amazing.