I don't think there really exists a best first move in chess.
e4; main move?

Ok, maybe by 4 centipawns. e4 opens up two lines, but early queen movement is often not good and white after d4 can safely play 2 c4 to attack the center and try to gain more space there with eventually e4. With e4 you don't get this luxury although 2 1 e4 e5 2 f4 is an opening at least. e4 there are more chances for early attack, but of course this is can only be taken advantage of if your opponent makes a mistake. So d4 is definitley the slower one but not worse. I hope people don't just play e4 because they think it's more logical. 4 centipawns won't help if you don't like the positions after e4.

To be successful at the top level, you are going to have to play a bunch of first moves to keep your opponents guessing.

That would help (though fischer had a pretty narrow repertoire) but how does that make e4 the best move? Anyways you can only go by your preference of move because both are almost exactly equal in terms of how good it is for white.

In chess 960 apparently sometimes black is better. I know the positions are different, but what kind of position would that be?

Are not chess openings a sequence of moves?
Is not 1. e4 just the opening move that dictates the opening to come?
That being said, I personally find d4 and c4 openings to be boring as white so my money is on e4.

Yes. It is the most logical move in all of chess. It's best by test as Bobby Fischer put it
And yet, as most huge databases show, 1. d4 wins roughly 1% more than 1. e4.

But you'd have to make the 1.e4 players all play 1.d4 for awhile and make the 1.d4 players switch to 1.e4 if you really wanted statistically significant data.
Oh, wait!
*facepalm*
But you'd have to make the 1.e4 players all play 1.d4 for awhile and make the 1.d4 players switch to 1.e4 if you really wanted statistically significant data.
Oh, wait!
*facepalm*
Not necessarily. Your argument basically is saying that 1.d4 scores better because it is used by better players, thus skewing the data because the stronger players win down the line. But if 1.d4 is played by better players, this would be a suggestion that it is a stronger move... Not the most foolproof logic, but I think the main point here is that any study at the present or in the foreseeable future is going to be inconclusive.
Tricklev, what does your DB say about performance ratings?
(Furthermore there are several other explanations you can furnish to explain why d4 scores better... for example, e4 is played more, so people are more used to it... This surprise value is the reason that some of the most rarely-played, generally bad openings, such as the Sodium attack, score the best)

E4 is an offensive opening for people who want to grab initiative.
D4 is slow, better for people who like to slowly squeeze the life out of their opponents position.
I play E4 but usually try to remove my e pawn and then play my d pawn to gain central control.
also, E4 is good because it opens up a bishop and queen while d4 is good because the supported nature of the pawn allows for major central control.
Do you think that e4 is the best opening in chess?