The poutine at Mile End? Probably the best you're going to find in this city. The small, classic poutine is $9, which is a bit steep, but it's city-prices so that sort of makes sense (though it's only $8 at the Brooklyn location). If you're looking for just any old cheese & fries combo, well, you can go get your disco fries fix somewhere else. This is definitely the place to go when you're missing Canada.
(Please note: I do not acknowledge disco fries. And I will not discuss the differences between these two fry dishes with you. It's 2014. You should know what a poutine is.)