Which is better? e4 or d4?

D4 is better if you want to control the center, becuz it controls 2 main sqaures. and is protected by the queen, whereas e4 isn't.

E4 is better, play a kings Indian defense and it's gold. It opens up the queen and bishop. And you can always do the queens gambit as well.
Most folks who know what they're doing respond to 1. d4 with either Nf6 or e6, playing 1. ..d5 just plays into white's hands.
Of course, it depends on what kind of game you want. 1. e4 tends to lead to more open lines and more active piece play. 1. d4 tends to lead to a locked center and slow development. There are exceptions to both, and playing against either one black should keep those preferences in mind.

1...d5 is a perfectly good response to 1.d4 and played at the highest levels. It cuts down on annoying sidelines to deal with and can lead to sharp and complex positions in the center early on if Black wants them.
Based on the recent Yekaterinburg Candidates' Tournament 1 e4 was both played more and more successful. So 8 of the best players on the planet preferred 1 e4 and the results confirmed this.
Which is better? e4 or d4?
1.e4 reaches crazy sharp, attacking positions.
The Elephant Gambit arises from 1.e4 e5 2.Nf3 d5!?