Best response to the Philidor Defense (C41)

1. e4 e5 2. Nf3 d6 3. Bc4 · Black to move

What is the best response to the Philidor Defense (1. e4 e5 2. Nf3 d6 3. Bc4)? Black to move. See the top replies ranked by opening theory and real-game results, starting with Nc6.

The main theoretical reply is Nc6, reaching the Italian Game: Paris Defense.