Quality as in good food and atmosphere... then if you got the cash or recently won the lottery... Queue the Cheval on Rene Leveque or Restaurant du Vieux Port de Montreal on St. Paul just east of St.Laurent Blvd in the Old Port. You craving japanese Kaizen on Atwater.
As I don't frequent bars at all maybe some of the other members here can help you out.
For Japanese I prefer Katsura on de la Montagne, just below Sherbrooke. Excellent food and more traditional than Kaizen. From there you can just walk over to Crescent St where there are a number of bars for just about any mood you happen to be in. You can check www.montrealfood.com for restaurant reviews. The site hasn't been updated for a while but it should give you an idea of the restaurants available sorted by cuisine.