I routinely crave the veggie burger ("Soul Burger") from Hero and luckily the Queen Street location is only a quick streetcar ride away for me. I usually get the combo and put goat cheese, avocado and tomatoes on my burger, which is an excellent combination if you're looking for ideas.
I'm not personally a fan of poppy seed buns (Hero uses poppy AND sesame seeds) so if they could switch to all sesame seed - or seedless - buns, that'd be awesome and I'd change my rating to a 5/5!
Also it's open super late on weekends so it's a great spot to hit after the bar.
A word of caution: the washroom experience at this location is TERRIFYING. They're in the basement, and it's really scary down there - dank and desolate, with lots of uninviting steel and concrete pillars. Trust me when I say you'll want to get the hell out of there in a hurry and return to your meal :D