Decent knish above 14th St.?
I've also seen cocktail size knishes from knish nosh in Queens (my parents are from flushing and those are their favorites) at Fairway. Zabars has them, too, in the back of the prepared foods counter.
For restaurants, Artie's on Broadway makes a surprisingly good knish. The rest of their stuff is nothing special, but for some reason the knishes are not bad.