proably the bishop cos pawns can promote, queens can basically do anything, knights can jump over things , rooks are good for endgame and u would lose if you didn't have the knig
Whats your least favorite piece?

What kind of a foolish question is that?
All are imperitive:
The Queen and Rooks are obvious, hopefully.
The knight, as has been said, can jump over things (also can threaten the queen nicely)
Bishop to control diagonals and can be traded without too much thought.
Pawns...protect everything.
(I don't need to say what the king is good at, do I)
But I think my least favorite peice is the King
I don't really have a least favorite piece (if you're thinking in those terms you're not open to all possibilities in a game), but I often let my bishops work passively when they can.
WELL???