Based on its size, it's an immature cooper's hawk. A little hard to tell if its female or male, looks like it could be a female. A sharp-shinned hawk has pencil thin legs, and their eyes are too big for their head. If we could see the tail we would also be able to tell, cooper's have a long rounded tail while the sharpies's is sqauirsh with a notch in it. A goshawk is a very large accipiter (family the cooper's and sharpies belong in) and the male goshawks are the size of a big female cooper's hawk. Merlins are very small falcons, the biggest of it's supspecies being the prairie or richardson's merlin. Here's a pic. of a merlin vs. a cooper's hawk in flight.
Blake
WA