Chamonix: best North faces?

What are your favorite north facing routes in the Chamonix area? I hear that the Argentiere basin is the place to go but are there any others that are recommended? Any grade beyond simple snow, just looking for classics.

Keep in mind that the warming in the European Alps changes things. So what was a "classic" 20 (or even just 10) years ago, might be now climbable only in rare good conditions.

Also the prime season in many recent years might have shifted and shortened.