My significant other says he would rather fight the giant chicken, not because it would be easier but because it would be awesome, kind of like fighting a dinosaur. If it's the same mass as a hippo (a couple of tonnes) but chicken shaped it would be really, really big. I guess the fact that a chicken can only see out the sides of its head and not to the front might work in your favour, and if you could take out one of its legs it would fall over.
Little hippos would be mean and have a vicious bite to them, but to have the same mass as a chicken (which really don't have all that much to them under the feathers) they'd be pretty small, like guinea pig sized, which doesn't seem all that much of a threat, especially if you have a big pair of stompy boots.