Best response to the English Opening: Symmetrical Variation, Ultra-Symmetrical Variation (A36)

1. c4 c5 2. g3 g6 3. Bg2 Bg7 4. Nc3 Nc6 · White to move

What is the best response to the English Opening: Symmetrical Variation, Ultra-Symmetrical Variation (1. c4 c5 2. g3 g6 3. Bg2 Bg7 4. Nc3 Nc6)? White to move. See the top replies ranked by opening theory and real-game results, starting with Nf3.

The main theoretical reply is Nf3, reaching the English Opening: Symmetrical Variation, Three Knights, Fianchetto Variation.