Thats a tough question, Ian. All the big waterproof/breathable fabric makers have done reams of studies trying to show theirs is "best." But there are so many variables, its tough to say what jacket will work best on a given day, let alone on a regular basis. What is the temperature? The humidity? Is it raining hard or drizzling? For how long? Are you active or sitting still? And on and on
Strictly anecdotally, eVent works very well for me. Its a material that is chemically similar to the PTFE in Gore-Tex, but that has a "secret sauce" that makes it more breathable (or so say the eVent folks). But its hard to find. British Columbias Westcomb makes some lovely pieces that use eVent. The Specter LT Jacket ($300) is a cleanly designed, all-purpose jacket that weighs a mere 12 ounces. Westcomb also does some innovative things like combining eVent with fabrics from Polartec and other makers, so you get a mix of hard shell and soft shell properties. The HX Flex Jacket ($350) has eVent on the shoulders and arms to shed rain, and Polartec Powershield around the torso. Thats a pretty potent mix of breathability, waterproofness, and stretchiness.
That said, Gore-Texs relatively new Pro Shell material is, in my experience, on par with eVent in all the important attributes. It reaches its ultimate expression in Mountain Hardwears Argon Jacket ($450). Yes, that IS a lot of money.
Then we have the Aegis, by which I think you mean the Marmot Aegis ($140). It uses a proprietary fabric called MemBrain that is designed to react to body heatwhen youre cool, the pores in the fabric close up, and when youre active, they open so water vapor can escape. I havent used a MemBrain jacket for several years, but the stuff does seem pretty effective. The Aegis also has so-called 2.5-layer" construction, meaning it has a two-ply laminate, with an inner half-layer of tiny dots that hold the fabric a little bit away from the body and that helps reduce any clamminess.
Waterproof soft shells I dont understand. Some makers take a waterproof/breathable shell, add a very light layer of insulation to it, and call it a soft shell." To me that just creates a really warm rain jacket, which maybe we dont really want. I prefer soft shells that dont pretend to be fully waterproof, but that breathe really well and act on their own as light insulation.
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