So lets say I am white, and I open with 1.e4. Black responds with 1...e5. What would be the best move to get me into the best opening position?
General consensus (including engine's) is that 2. Nf3 is strongest. Many other moves are also playable for the vast, vast majority of chess players. For example, 2. Nc3 and 2. Bc4 are quite playable (many other options). Play 2. f4 if you're looking to take souls (but know it is a double-edged weapon).– SecretAgentManFeb 8 at 20:28
Chess isn't a solved game so it's hard to give a definite answer. However experience tells us that 2.Nf3 (developing a piece and targeting the e5 pawn) is the preferred choice by strong players. 2.Nc3 and 2.Bc4 are probably just as good but not so flexible (for instance with 2.Nc3 you don't get the opportunity to play a quick c3+d4 plan).
Gambit lovers may also want to try 2.d4 (to get into a Danish Gambit after 2.exd4 3.c3) or 2.f4 (the King's Gambit)
You can explore a bit here