Best response to the Vienna Game: Stanley Variation, Three Knights Variation (C28)

1. e4 e5 2. Nc3 Nc6 3. Bc4 Nf6 · White to move

What is the best response to the Vienna Game: Stanley Variation, Three Knights Variation (1. e4 e5 2. Nc3 Nc6 3. Bc4 Nf6)? White to move. See the top replies ranked by opening theory and real-game results, starting with d3.

The main theoretical reply is d3, reaching the Bishop's Opening: Vienna Hybrid.