The title says it all

Pawns are the frontmen, but have very little options for defense.
Knights come in handy, when the opponent is slipping up on his moves.
Bishops always work in a diagonal advantage, sneak attack!
Rooks always helped me block in the pieces I wanted to take.
The king can provide protection for other pieces, as long as he, himself isn't left open for attack.
The Queen has the most options for movement, but you don't want to just throw her out there.

I'd say the king wins, with strategically defending the others as long as the other pieces can defend him as well. You have a smart offense with just being double defense. The king is always my most important piece.

I'm saying pawns because, if you have enough, you can always comeback from really bad mistakes that happened early. But you still need to play defensive to try and save them.
I usually always move at least one so I can get my queen and a bishop out. Then leave the front line held up by pawns. And usually, I have it set up so I can get my knight to take his spot, which leaves nothing wide open for the opponent to have an opening.
Although this is the way I usually, play; I'm really not that great at it. Just play it for fun on game night.

Pawns are by far the most usefull piece. (Not the most important)

Pawns... Little defense options? I don't think so. Pawns are useful as hell.

I think the most useful peice for me is the bishop, but I need to have some pawns on the board in good places.

Knight by far, I can get in and destroy pieces without having to get too close AND their good for psyching out the enemy. Trust me I have won numerous times just for the simple fact of having the psychological advantage over my opponent.

Once you have your Rook through the opponent's lines, you can cause a lot of problems. I voted for the Rook instead of the Queen due to the fact that there's two Rooks; the Queen can only do so much.

I agee. The rook is mostly used for the final few blows through an enemy's line of defense. Once there, the rooks can basically end it. The rook is my vote. ^-^

queen is the most versatile and powerful

the knight is a close followup as it can be used for deadly forks

Depends on what part of the game you're talking about.

I prefer bishops, overall, because they allow you to lock down your opponent, and are very useful strategically later in the game. Bishops are able to cover more spaces than knights, making them the more useful of the two, in my opinion.

Knights are however good for blitzing the opponent, and, for what ever reason, people seem to concentrate more on the knights. Perhaps its the fact that they look like horses which draws people's attention, idk, but, they too have their uses. I prefer them marginally in the beginning, as they are useful for taking control of the center.

With my particular playing style, I like the rooks. I play in a Paul Morphy-ish style, taking advantage of gambits, and forcing the other person to react. Opening up the lanes for the rooks is one of my particular strategies, as the rooks are devastating at any point when unleashed. They aren't really game changers, but, they can take people by surprise.

The Queen, is my favorite piece, but, not the most useful by far. The queen has her uses, my favorite being the fear factor, as people seem to concentrate on her more. Having her in a threatening spot is always good enough to illicit a reaction from someone, despite whether or not it was my intent to harm them with the queen, thus, making it a very useful piece in that respect.

The pawns... are... well, there. They have plenty of uses, but, don't really thrive at anything.

Out of the choices, I'd rank them like this:

1. Bishops
2. Knights
3. Queen
4. Rooks(interchangeable with queen, which marginally overtakes them because of the fear factor)
5. Pawns
6. King