What is your favorite color for your bag? It seems like coffee is the favorite for the MEI bags, but how about for your Airboss? I'm torn between olive, khaki, raven (black), or coal...

The darker the color the less travel "goo" shows. That's why so many bags are black. My advice is to get a dark colored one in whatever shade you like.

I got the Air Boss in black, like I get every piece of luggage, business or personal in black.

The color doesn't attract attention when traveling, doesn't show dirt, can be used in a business 'situation'.

It's your bag, your color choice and if you have a preference of your own, get the color you want.

For me, a bag is used to haul gear and items and if it's inconspicuous, so much the better.

I purchased the Air Boss in the Midnight color. It is a very nice shade and is useful for both business and leisure use. I get compliments and admiring looks all of the time. Jerry S. is correct in that the darker color does not tend to show dirt and things like that. Whatever color you choose you will be getting in my opinion the finest bag out there!

My Air Boss is also Midnight, for the same reasons. My wife's Sky Train is Forest...not quite as dark, but still good at avoiding stains, and not standing out too much in a crowd.

Generally speaking, I prefer slightly unconventional colors for my luggage. That has actually saved me when I was forced to check a bag--right after the so-called liquid scare. Because of my red bag, I quickly spotted it on the carousel.
I don't know if the carry on bins are still getting prematurely full. If you're forced to check, trying to find a black bag in a sea of black bags is a pain in the ass. Granted you can attach a bright colored ribbon or another identifier, but that seems to defeat the purpose of getting a black bag--imo.
I'm thinking of getting the Western Flyer. If it turns out to meet my specifications, I'll be getting it in slate.