Looked around on Yelp/Eater for some recommendations while in town, and the Harbord Room (and the famous burger), surfaced to the top of the list. I did an early Friday dinner and ordered the burger and the Ronald Clayton. The burger was excellent: meat was fabulously tender, and cheddar + aioli = rich + tangy. The slaw was a little less flavorless but nicely cut...but the homemade aioli and ketchup? Best I've ever had.
Service was super friendly -- in fact, they gave me a list of recs for other places to try. Even if the burger wasn't already awesome, I'd definitely come back because the staff really did a great job of making the experience there so comfortable. You go, Harbord Room!