Opening

Tell the most unique but powerful opening.

it depends on the person who plays the opening because all openings have disadvantages and advantages. For example we get the Italian game and it has the advantage of is an opening that gives you different positions after it so that you can practice many positions, but the disadvantages are that the middlegames can be hard to play at times, can bait players to just doing the fried liver and not really learning, and at intermediate almost all players are prepared against it. What I am saying is that if you like the advantages and don’t mind the disadvantages much then the opening might be a good one for you and don’t forget about the style of the opening and if it’s not your style like for example positional style then it’s not for you unless there is another line that can’t go to your not preferred line in any way. I will say more examples of disadvantages and advantages. Advantage examples: easy to play middlegame and opening, is a system opening, gives different after opening positions to practice other positions, matches your style, and not baiting players into just trying to trap players. For disadvantages you have hard to play midgame and opening, doesn’t match your style, leads many players into just trapping people, and not a system opening.

Yes,Josh11live is correct

One word: Bongcloud

"Josh11live " is correct. There is no "all powerful" opening.

Below 2500 elo (who amongst us gets to that level?) just about every opening is playable.

Every opening has trade offs...

An example.

The London: You develop in a wrote fashion, then from an established position, you play chess. (appeals to players who like to have a known pawn structure to play from) Never mind the people who say "Black equalizes easily" (Every defense, if played correctly Black equalizes) if you understand the themes of the opening that is what matters. Period!

It's about cutting down the number of times you are rolling the dice on deciding what to do. (at that point, one is just guessing...) 

What I see (and What I have done also... hence learned it was wrong) I see people playing openings they don't understand, that are way too complex for them. Again... it's about cutting down the "I feel I should play here... "You need to know...

Example the Sicilian or the KID. Both are great openings, but IMO not for beginners, Both produce such complex positions that GMs can struggle finding the right moves. I've seen the argument "When two low club level players are playing one of these openings, both are just thrashing about , they cancel each other out ... (in reference to the opening phase)  The logic that both are rolling bones, praying to the chess gods for a win... so it doesn't matter, doesn't really compute with me. Why do that when one can find and take on an opening they can understand?

There are also  NO OPENINGS that are boring .... that's a crap notion, stated by players who for many reasons, of which, none of them are valid! One can play passive and make the game boring, but one can also play aggressive and make the game sharp! I've played against good London players who are aggressive, very tactical, won some. lost some... IT's not the opening... it's the player! (It's also THE PLAYER MAKES THE OPENING... NOT THE OPENING MAKES THE PLAYER!) 

My advice... pick an opening that you can understand. Look at the pawn formation, know the in's and out's of it e.g. where what pieces go where to launch attacks on the opponent's King, what pawns in that formation can be push forward to attack with. What is the typical endgame that you can reach. Then.... look at that pawn formation and the piece development in relation to what if your opponent opens differently... look to see what minor changes you can make to address what they are doing (sometimes it might big changes where your development might have to be totally different ... But at that point ... YOU will know the why...

Use ENGINS only for blunder checks after you have SELF analyzed (and then... when doing so Don't get frustrated when they are always trashing your analyses ..... they are 3000 elo plus... they do that to GMs also. And.... never EVER formulate an opinion of an opening on what a engine evaluates it at. Example ... Engines evaluate the Englund gambit as less that optimum (Remember I stated all openings are playable below 2500!)  Someone playing the Englund Gambit, that has specialized in it (once you get above a certain ELO) will know the in's and out's of it, He/she will what know and understand what lines to transpose to avoid a bad position. They win with it... because They are NOT rolling bones and praying to the Gods of chess... but playing the position based off of what they know and understand.

I recommend to learn a bunch of openings not to be used as your main, but to be used to learn different positions, pawn structures, and piece placement

But don’t go too deep. You should instead try to use what you learned in there and you should study openings that have the difficulty of KID opening so that you can get used to those because those are instructive. There are many learning ways and this is one that I’ll recommend, but others may agree or disagree. It’s mostly your choice and keep in mind there is no best answer