Resign. Lol, just kidding. Maybe try c5?
Best defence against E4

e4?? f5!! -2 advantage for black and then if exf5?? g5! -94.2 White will get so confused he will lose on time, trying to figure out if Qh5 mates. That's why d4 is better. d4 f5 is the dutch defense, while after d4 c5 dxc5 b5 , Ka5 is an illegal move.

the only reason why a6 is best is because e4 is a blunder and anything is better than it (sorry e4 fans, im a d4 player)
Hi832, did you know that 6 of 10 games in the Carlsen - Anand match opened 1. e4?
FACE PALM
I just can't see these topics anymore, it kills me. If we would know chess would be already solved.

The only valid answer to "How long is a road" is "The secret is really to force your opponant to play to your strengths." given above.
Look at openings and find one that produces positions you like - that is the best defence for you. Top GM tounge-in-cheek answer is 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 ½-½ if you enjoy boring endgame torture. Me I'll play the french MacCutcheon 1.e4 e6 2.d4 d5 3.Nc3 Nf6 4.Bg5 Bb4!? or the open Ruy 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Nxe4 ...

FrenchTutor -
The e5 Nimzowitsch looks really interesting, and I don't think I've ever seen it before! I'm assuming that the idea is usually to try and infiltrate through the weakened dark squares in the middle (c3, d2, e3, d4) combined with a center-break through the c6-c5-c4 corridor? What do you do with the ugly little donkey on g6? Does he go back to the center or is he going to be stuck sitting on the bench unless white lets us exchange?
Its a matter if taste really, i prefer Caro kann Smyslov, Korchnoi, and Bronstein-Larsen variation, pretty much anything besides the main line.
The Sicilian is by far the best, especially for beginners.
Why? If you are facing players under 1500, you will almost always face 2. Bc4 from a lazy White player, which pretty much always guarantees Black a good position after the reply 2…e6 followed by …d5. Against the Grand Prix (2.Nc3 Nc6 3.f4, another popular lazy line), 3…e6 4.Nf3 d5 5.Bb5 Nge7 6.exd5 Nxd5! gives Black a good game.
Against the main line, I would recommend the Taimanov (1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6 5.Nc3 Qc7). Most amateurs will mistakenly take on c6 early (5.Nxc6), after which we take with the b-pawn and push d7-d5, with a superior game for Black.
At higher levels (2000+ FIDE), you will start to face well prepared players. You might want to check out some chessable courses on the relevant main lines.

I can't really say because I'm at the beginning of a new Chessmaster tournament in 5m+30s per move with notably all the ai.GMs (I don't play, I watch the Chessmaster tournament) but it will most likely be among these four moves :
A : 1)...c5
B : 1)...e5
C : 1)...e6
D : 1)...c6
For the human GMIs, I think and I would say that it must be played between these two moves :
a : 1)...c5
b : 1)...e5
In the Youtube videos I've seen of Magnus Carlsen against GMIs (with black against 1.e4), he often plays 1)...e5.
In an opening encyclopedia it informs that the GMs play more 1)...c5 than 1)...e5.
Anyway if we don't have a super super super calculator who has calculated everything etc. it will remain an opinion or a belief more or less relevant.

Honestly, it depends on the kind of game you're better at playing. The current fashion is to have open games, with big sweeping moves, often employing pins and strong tactical moves, obtaining advantage of high-trafficked squares. To these players, a highly positional game, where many small moves are required, they cannot comprehend. Of course, the opposite is true - if you are a positional player, open games tend to be a problem. The secret is really to force your opponant to play to your strengths. Which is best?? The one that works best for you is the one you should use, but you have to know all the options anyway. Always use the openings you understand, when it counts. Club play etc is for working on your new openings.
110% in agreement! It's so annoying when people state unequivocally "this opening is best and that one sucks" like theirs is the only correct opinion. finding an opening that matches your style (once you get one!) is very important. i'm a tactician, so i only do open gambits when possible. incorrect haters parrot the GM "gambits are unsound" mantra, but under 2000, gambits are STRONGER! most top gambits have stats that are +8%! that's HUGE!
i'm seeing more and more too that sometimes the "strongest move" actually performs the worst over the board, and the move that -1.7 actually wins more. one has to factor the human element and the lack of perfection under 2000.
i don't agree that the sicilian is the best at all. it might be for grandmasters, but there's way too much theory to start out with unless "your style" includes an opening book the size of an unabridged dictionary.
to me, ANY opening that allows 2...e5 sucks! if i can't play Nf6, i'm raging. i hate closed positions. for ME, open games are the only correct option.
i want to drop the scandinavian because I hate 2...e5 there and want to play 1...e5, but then i need to learn the spanish, 2 knights and stuff from the scotch and others too. i'm still trying to book up on my current repertoire.
the sicilian is best for sicilian players. personally i don't like that i have to play it from the scandinavian. why would i want to play nothing but c5? yuck!
looking at 1600-2000 performance stats, actually, the alekhine is a gnats hair stronger than the other 1.e4 replies, but that 1 percent "edge" means nothing as you have to follow the theory to see where it goes. lines that look strong can turn on you after half a dozen plies and lines that look weak can turn winning in a couple moves when you follow the best line.
"best opening" is purely subjective
All burger references aside, there have been some attempts at a salient answer to the orignal question but again, as anyone asked and or tried to find out how good or bad the thread owner actually is? I ask you, some people have suggested the Alekhine which, in itself, is not a bad one but if the person concerned is a player with a 3 figure rating then suggesting such a complex opening is a recipe for utter disaster....