I'll add my voice to the crowd and agree that Naina's is where it's at when it comes to burgers and poutine in this city. Come prepared for a huge, delicious meaty meal and you won't be disappointed.
It's a tiny (but clean) little hole-the-wall in the Ogden Rd industrial area, with a comfortable, cheerful ambiance. Order at the counter, then find a seat in the small dining area and they'll bring your food to you. Our server was very friendly, joking around with us and giving her food recommendations.
The stuffed burgers are sooo juicy and good (and massive) -- I had the bacon mac 'n' cheese stuffed and I'm looking forward to trying other combos. The poutine was seriously some of the best I've ever had. The fries tasted super fresh and were perfectly done, and the gravy was very flavourful without being too salty. Just go, it's well worth it.