I went to Jack Astor's Bar & Grill at Yonge and Dundas and LOVED it! It gives you an amazing view of the hustle and bustle in Toronto and is affordable to boot :)
Curated list for you! http://www.blogto.com/toronto/the_best_rooftop_patios_in_toronto/
There are MANY great rooftop patios in Toronto but one of my favourites is called The Pilot.