For me, it's a toss-up between "North By Northwest" and "It's A Mad, Mad, Mad, Mad World".
"The Other" is also an excellent looking DVD.
I have a few Noir films myself, but I can't remember offhand if any were particularily good image-wise. I recently watched "The House on Telegraph Hill", but I'd have to watch it again to see what I though of the DVD quality.
I usually don't notice that stuff the first time through unless it's really good or really bad.