I prefer an EDC bag to be leather and relatively small. I recently bought these 3 bags and will be keeping 1 winner:
MS Collection - Manbag
Claire Chase - Manbag
Rustic Leather - Manbag

I have been tempted to buy one of these bags for going super light:
Vagabong Traveler - Shoulder Pouch
Rustic Leather - Shoulder Pouch

If I carried an iPad (which I don't), then I would buy this bag:
MS Collection - Manbag for iPad

I'd like to have this Maxpedition for light hiking or biking:
Maxpedition - Manbag

Having the right EDC bag is important to me because it is the only clothing I don't change day-to-day. Of course, bags are highly personal, as everybody has their own needs and style.