There is no "best" opening.
what is the best opening?

And furthering MrEdCollins' post, there is no one best opening. But a best opening for how you play (and if you know how your opponent plays then you can choose an opening that will force them to play out of there forte style.)

sorry i shouldnt have said "best" more like the most useful opening, and not in fact form i want your guys's opinion.(PS: this is for white or black or both)

White 1.e4
Black 1...c4/e5
OR if you're advanced try 1...e6
Just use options that aren't discussed in text book as it will throw your opponent off. Like for example I have a friend who only studied lines of 1.e4e5 so I started playing moves like 1...c5/e6/d5.

Even if you know it better than your opponent, your opponent may have a better middle-game/end-game than you. Just play an opening that you're familiar with already and then just progress from that. Try reading Opening theory books that I'm sure you can get at any Library or buy online. And perhaps if you are a better player in the middle-game/end-game then you'd be better studying text book theory about that.

Even if you know it better than your opponent, your opponent may have a better middle-game/end-game than you. Just play an opening that you're familiar with already and then just progress from that. Try reading Opening theory books that I'm sure you can get at any Library or buy online. And perhaps if you are a better player in the middle-game/end-game then you'd be better studying text book theory about that.
If you play an opening that your opponent is not familiar with they will not be familiar with the middlegame that results. If your tactic and positional ability is not there then the "best" opening will not do anything for you. I have beaten multiple stronger players because they did not know the middle game my openings transposed into. What is good in one middlegame is not neccessarily good in another. I think comfort plays a big role in chess. If you give your opponent a position he or she does not know, they may get uncomfortable. I remember analyzing a game with someone and he told that he had no clue what I was planning and it exerted pressure on him, causing him to mess up....

please tell me
For beginners, the best opening would be to develop all your pieces early, connect the rooks, move each piece once, don't move your queen out too early. At your level, why would you waste your time about best opening? Why not follow basic opening principles, and concentrate more on tactics and end game.
please tell me