Mountainsmith Eclipse 55
Light enough for thru-hikes and tough enough for bushwhacks, the Eclipse combines an ultra-simple packbag with a solid suspension and reinforced, cushy, memory-foam hipbelt. The result is a versatile pack that can be overstuffed to your heart's content, thanks to superb load transfer, yet still feel at home on a light-load weekend. The streamlined packbag never snagged, not even when one tester had to thrash through a dense willow thicket by headlamp. Huge mesh holster pockets are easy to reach, and each one is large enough to swallow a hat, gloves, bars, and GPS unit all at once. The X-shaped frame stays require custom bending, but they're easily accessed. Nitpick: The cordlocks on the holster pockets should be captured for one-handed adjustment. $199; 3,417 cu. in.; 3 lbs. 8 oz.
ARC'TERYX Khamsin 50
This climber-friendly pack is dialed for alpine duty, yet it's still comfortable for trail jaunts. The belt, lid, and backpanel all strip off to shave a pound, and the packbag is made with scrape-proof fabric. The giant clamshell-style "crampon" pocket is a standout–big enough to swallow a small sleeping bag or pad. There's a full-length side zip for quick access in crappy weather, and both the lid and main compartments hold a ton (the capacity is underrated). As with most stripped-down alpine packs, the Khamsin lacks bottle pockets, hipbelt pockets, and wand slots. And though it'll carry 45 pounds, the thin, soft hipbelt is tuned for mobility, not weight transfer. $275; 3,356 cu. in.; 4 lbs. 9 oz.
Backcountry Access Stash Alp 55
A perfect ski pack needs great stability, versatile carrying options, and a hydration system that doesn't freeze. The Stash Alp 55 has all that, and more. After a four-day yurt trip in Idaho's Pioneer Mountains, one tester said, "Even filled to capacity, it handled 35 pounds comfortably despite a thin hipbelt. And the ski-carry attachments let you haul planks in several positions." The shoulder straps have an internal hose routing tube for cold-weather hydration, and the Nalgene-compatible system lets you swap out drinks during the day (but requires more frequent refilling than with a large bladder). The hipbelt pockets hold wax kits, and a cavernous front pocket swallows shovel blades and wet clothes. There's also a vertical pocket on one side for avalanche probes. $165; 3,356 cu. in.; 3 lbs. 5 oz.
REI Venturi 40
"Everything you need for big dayhikes and lightweight weekends, nothing you don't," said one tester, summing up our take on this versatile pack. Like others with a "trampoline-back"–a mesh panel that lets air pass between your back and the scooped pack frame–ventilation is great. Unlike many others, internal capacity is also good. Other details are dialed: A well-padded shoulder harness and reinforced hipbelt deliver carrying comfort; rubberized fabric protects high-abrasion areas; and the shoulder yoke attachment is reinforced for rock-solid stability. Bummer: While it's made to hold 3-liter bladders in two places, only the inside pocket worked; bladders slide sideways out of the exterior space. $129; 2,441 cu. in.; 2 lbs. 12 oz.
Black Diamond Speed 40
When is a pack not a pack? When it disappears on your back like the Speed, yielding the best freedom of motion we've seen in a pack this size. "The harness is totally out-of-the-way," reported our tester after hauling the Speed for a scrambly three-day trip through Utah's Waterpocket Fold. "And the packbag's so narrow you could run with this sack and not hit your elbows." The molded foam backpanel and ultralight tubular aluminum V-frame can handle 35 pounds, and stability is decent if the load-lifter and stabilizer straps are cinched. Not surprisingly, features are spare: just a hydration pocket with a smart, nape-of-the-neck hose port, and a three-pocket top lid that floats via simple aluminum J-shaped hooks. Minor demerit: The soft backpanel turns convex when the pack is loaded with a full water bladder. $130; 2,500 cu. in.; 2 lbs. 8 oz.