E4 or D4

1. e4 is better. 
The bishop it opens up prepares it for castling, and if the opponent plays e5, we can start showing who’s boss with Nf3. Showing right off the bat that e4 is meant for people who want to play for the win. I play Four Knights Scotch personally, it’s reputation as being drawish is completely incorrect.

As for other responses to e4, the Sicilian can be handled through the Moscow/Rossolimo, the French falls to the advance, and the Caro’s heel is the Fantasy Variation. The Pirc is objectively a decent try that is harder to defeat, but gives up the center and the Austrian attack can be a powerful weapon.

d4 just isn’t lie that. I play the Benko against it, which can prove much different than other d4 openings and is one of the most sound gambits. Against d5, d4 players just don’t get it done, and QGD and the Slav are proven ways to hold against d4.

Basically, d4 is much more drawish, while e4 goes for the win. The Sicilian shows how in an e4 opening both players go for the win, isn’t that we should all be doing? So yeah e4 is much better, no doubt about it.

Not that long, just had to think about what I wanted to say. Just trying to help a fellow player, I’ve flip flopped openings quite a lot but since I came back I’ve been playing e4 and it’s been working.

At my level, most people who day d4 are folks who tend to focus way too much on openings. They don't realize that your knowledge of the London System isn't going to help you if you don't know what you're doing past that point. Of course, there are exceptions, but it seems to happen a bit more often than it does with e4 players.