I'm digging the Goruck GR1 backpack. I got it a couple months ago for a photo trip to Yosemite, and I've used it ever since for everything from hiking to business trips. It's now my go-to bag for traveling and anything outdoors. For business trips or other travel, it carries enough clothes for a 4-day trip, plus a MacBook Air and everything else I need, and it's small enough to fit under a seat in an airplane. For walking or hiking, it carries my pro-sized DSLR with several lenses, a tripod, a jacket, food, and water.
Did I mention that the GR1 is tough? Made of 1000D Cordura, it's practically immune from abrasions, and it's water- and mud-resistant, too. I walked in the woods during a steady rain for over an hour today, using it to haul a small camera and tripod along with a 1.5L water bottle and whatever else I left in there from my last trip. As you can see from the photo above, the outside of the bag was fairly drenched towards the end of the trip, but the contents remained dry and well protected.
At $295 plus shipping, the Goruck GR1 isn't cheap. But it's a tough bag that's comfortable to wear. It looks great, it holds a ton of stuff, and it's made in the USA. For me, it's just about perfect.