For traditional sushi, the top three are generally Yasuda, Kuruma, and Masa. Second tier includes Sasabune, Sushi Rose, 15 East, and a few others in midtown. Under that you can get into Gari, Ushiwakamawaru (sp), Geigha, etc.
Yasuda gives you the best bang for the buck, especially at lunch.
If you're looking for rolls or sashimi, disregard all of the above.