4 out of 5 of my backpacks are Osprey. It's all I buy now and I love my Quasar backpack. I have this for everyday carry for my laptop etc and use the Timbuk2 waterproof backpack (which is also awesome but not quite as much) on rainy days.
When we lived in the UK, and were working from cafes we would walk to 'work' in the rain every day. After a few months of using a rain cover on my Osprey backpack, I just bit the bullet and bought one of these waterproof bags. And loved it.
Just the best satchel I've found. Great compartments, comfortable to carry, looks smart, and is waterproof as well. Perfect carry on flight bag as well as everyday carry for your laptop. It's what I use, but check out the reviews for yourself.
The TIMBUK2 Commute Messenger Bag comes in a range of colors and styles. It also comes in small, medium, and large. The 'small' size is perfect for every day carry. That is the size I have. The medium is great for travel as carry on luggage. But the large is just too big for anybody but a bicycle courier or mailman. :-)