I struggle with "bests". But as of right now, this is my favorite restaurant in Pittsburgh. Their menu has a lot of originality and creativity in it. There's a nice balance of foods and everything I have had there has been wonderful.
Best brussel sprouts in the burgh, and there's LOTS of competition
Pig Candy is a must try.
And of course...the rye flight.
Staff knows their business. The young woman who waited on my sister and I during our most recent visit impressed me with her knowledge of the menu and the bar, steering us deftly toward options that satisfied our palates and warned us of impending danger (one example: "they say that one in twelve shishito peppers is really hot, but lately they've been trending a bit hotter" - in response to my sister's question regarding whether the shishito small plate might be too spicy for her)
If there's any downside it's that some of the seating is cramped and shoulder to shoulder with adjacent tables. And it's noisy, which might stand between you and that romantic evening out that you'd planned. If you make reservations far enough in advance, a table of four will get you seated beneath the "antler chandelier" where the tables are a bit larger and the elbow room a substantially improved. But if you don't mind lifting your voice a bit, and making new friends, then I think Butcher is lock for a great night out with a friend.