Which chess piece is the most powerful?

As always it depends on the position, but generally it's the Queen.  Most players at your rating wouldn't need to ask...

The king, obviously.  Without his supervision, the game is over.

There is, however, a decisive difference between "powerful" and "important". I would claim the Queen, being quite versatile on the board, would be the most powerful most of the time, whereas the most important piece is always the king - regardless of the board condition.

Basically, the woman has all the power, but has to go running around looking after the man all the time, because he's the breadwinner.

The queen is the most powerful..

the female of the species is more deadly

This does seem to be quite a good point.

The queen is most powerful on the board but when traded off then the rooks become powerful it help the endgame.

The one that delivers mate?

the pawn...

Not cause I actually believe that, but because this thread is in need of a controversial answer.

 obviously 'd queen, but then combinations of some lesser powerful pieces makes them 2'nd...

If she has to go running around looking after the man all the time, she is a slave with little or no power.

everybody, mostly, says the Queen is the most powerful.

has somebody thought about a Pawn, which can become/be promoted as a Queen?

The Bishop.

Sunill, are you being purposefully stupid? A pawn can be promoted to a queen - but a queen is already a queen. Come on, dude.

 I agree: it can be promoted as a queen, but as a knight , a bishop or a rook, too . This skill is sometimes usefull to avoige a drawn.. Moreover, if you and your opponent are equally good, just a pawn's promotion can give you the victory.

What about a Knight, It goes over the top.

Hear, hear!

If one defines power, to have the most strength physically, then teh queen is certainly teh most powerful. This is because it has the largest natural range of any other piece. Other pieces, like pawns, maybe versatile, but they are not as powerful as teh queen because they cover less ground at any given time. Additionally, the piece that delivers mate, is not necessarily the most powerful. It maybe very important, but a pawn still has less strength, which is quantized in this game by range, and is therefore less powerful than any other piece.

Queen of the Night is a piece from fairy chess, it is a combination of queen + nightrider. It is way stronger than queen.

Let's stay aside from fairy pieces like Kraken or Universal Leaper.