1. e4 vs 1. d4
Always an age-old question for me especially that I seem to prefer 1. d4 but my heroes, Bronstein and Stein preferred 1.e4 players even though the former also plays 1.d4 a lot. In my actual experience, online as I seldom play OTB, 1. d4 allows a freer game, more space for the pieces to maneuver which provides more options to attack. In the case of 1. e4, maneuvering space is somewhat constricted and scope of the pieces are more restricted especially in many variations, of the French Defence. And if I play 1. e4 to generate an attacking game, I would not want to play the so-called Anti-Sicilian Systems. And why did Bobby Fischer preferred 1. e4? My guess is that with this opening, he could take advantage of his superior knowledge of the sharp lines of opening theory against his opponents because of his devotion to a study of the games and reading a whole lot of chess journals including the Shakmaty v. SSSR (Chess in the USSR). In this Internet age, I doubt if he would still exclusively open with 1. e4 had he been playing today.
I used play e4 but got blasted with the Scandinavian and switched to d4 but then switched back cuz I'm more tactical.
1.d4 players prefer to slowly take over the castle, while 1.e4 players like to crash through the door and attack as fast as they can.

I've spent some time recently trying out e4 and I find the Ruy Lopez and Itlian games can both me much less tactical and much more strategic than d4. So really it probably comes down to which opening give you a playable position that you understand well enough to take into middle game.

I play d4 now. Played e4 my whole life. I prefer d4 and the only thing I really miss is cracking the following:
Oh, how I miss that blunder.

"I almost always play d4. It is protected, and it is definitely NOT boring"
It depends of the lines you are choosing (IMO the Tromposky is maybe more funny to play than the exchange slav, though this latter can be interesting). It also depends on what you find boring. It is simply a matter of opinions.
1.e4 or 1.d4? 1.c4
It might depend on the style of play
I personally love to play 1.e4 more often but 1. d4 is also a very strong opening for a few of the best openings such as Queen's Gambit; Declined , London System, Grünfeld Defense

I prefer 1. d4 because I think it gives more of a choice of types of game, so there's more to know and it's more interesting. There's also more chance of genuine complications where the better player, or the luckier player on the day, has more chance to win. Finally, with 1.e4, "book moves" are more analysed, so people themselves aren't really playing, so much as following moves others have made. This happens to a greater extent after 1. e4.

both are playable at any level, even Alphazero plays both these moves, so I am content to say they are about the same value.
C4 may be too passive. It controls the d5 square (like e4 does) but doesn't open a diagonal for a bishop.