topshop's petite jeans are nice and are good value for money! I'm kind of short so I normally buy from there and warehouse sell some good ones too. topshop sells loads of skinny jeans and slim fit styles as well which would be good if you're quite skinny. I wouldn't recommend new look jeans cos every time I try them on they're really long and I always have to turn them up if I buy them and they come up big round the waist as well...
don't really know anything about American brands though.
American Eagle do very good jeans, as do Old Navy.
In Britain, I'd recommend H&M or Marks and Spencer.