I agree with @ezasucanget
If you think 1.d4 is always slow and boring, have a look at this cool gambit line:
Now, in all seriousness.
d4 players are cowards :P
For me, my choice is all about Open games, Semi-Open Games and Closed Games.
If the player is much lower rated than my self, I would think of e4.
If the rating is similar, I'd probably play d4.
If they are a bit higher rated, I'd try c4.
If the player is 400 points higher than my self, I'd try Nf3 to see their plan and do my best to make the game last long. I'd be searching for draw options, while trying to win.
I know both players can castle short, but it will be a mirror image. Basically I think it is best to play asymmetrically and try to control the center, so that the opponent must use the wings of the chessboard to go around the center, which will require a few extra tempos to get to their desired square. This effect is like saying pass your turn and you get to develop another piece, while the opponent will need to play the same piece twice to reach their aim.
For me there are 4 choices : A, B, C, D.
A) e4 c5 (Avoid .... captures)
B) e4 e5 (Block ... pawns from moving forward.)
C) e4 d5 (Counter-Attack ... immediately)
D) Defend, Delay, Development (Pawn storm, build a stone wall, get the pieces off the board)
E) Elude captures
F) Force the position
G) Gain material
H) Hope for the best move. That way you know what they are playing next.
More : Mobilize the pieces (not pawns). Then aim at something major.
The letters on the chessboard are for me mnemonic helpers.
When nothing comes to mind, the letters help me recall my options. ͼ( ⌣́,⌣̀)ͽ
A) d4 Nf6 (Avoid .... captures)
B) d4 d5 (Block ... pawns from moving forward.)
C) d4 c5 (Counter-Attack ... immediately)
D) Delay development (Pawn storm or build a stone wall).
Play a pawn to free a bishop.
Play a knight to protect the king.
Castle to mutually centralize the rooks and decentralize the king to reduce the possible lines of attack.
Have fun honing new pawn moves.
d4 and e4 both can be sharp or slow. If you like sharp games more e4 lines are sharp than d4. If you like positional games play d4. If you like being good play both. You will reach a barrier at one point and you will need to play both.
e4 best by test yuh
e4 is more fun to play, and in my opinion, leads to fewer draws. It's the more fighting and principled choice. I believe that e4 is the best way for beginners to play, as it leads to more open and active play where it's more easier to learn piece coordination. With d4 on the other hand, I give a big frown when I see beginners play stuff like the London system. From a beginner standpoint, I advocate playing e4 stuff mainly. However, I do see the reason for playing d4 later on, as Kasparov liked playing the Queen's Gambit (and mainly playing Isolani Structures.) My few reasons for disliking 1.d4 are the slightly higher draw rates (which I shouldn't care for at my level but I do) and not having enough fun. d4 doesn't give me a lot of fun as e4. To each his own, but I strongly advise beginners to not play 1.d4.
d4 = classical
e4 = everywhere where you wanna have fun :P