Via Mercanti is a great, casual little pizza place in Kensington Market. The food is always delicious, very reasonably priced for the quality.
The service is excellent. I have been here three times - once with family and they were so sweet to my parents explaining the menu, once with a friend during a rainstorm and they let us stay for a couple hours, just chatting and drinking our diet cokes until the rain stopped. This kind of service is so rare in Toronto.
It is maybe not the type of place that you would want to bring someone you wanted to impress (not at all fancy) but if you want great, authentic food in a comfortable environment - you should go to Via Mercanti.