Thanks for your interest in Arc’teryx. The Epsilon is a lighter/more breathable but less wind/water resistant garment than the Gamma MX. We used to produce a couple of jackets with Schoeller Dryskin called the Stinger/Javelin Comp. They were slightly more durable but less water resistant and less stretch than the Polartec Powershield. The Alpha comp is an even lighter/more breathable fabrics because of the lack of a thin micro fleece lining on the inside. The Alpha comp though is waterproof/windproof on the shoulders and waist areas with a much thinner Durastretch Tweave material (similar to Schoeller Dynamic) which makes the Alpha Comp the most breathable of the jackets. They would all be good for the activities that you stated but it depends what is most important, if Breathability is the most important than the Alpha Comp would be the best choice. If water/wind resistance is the most important than the Gamma MX jacket is the best choice. Finally, if you want a jacket for overall use and price is a factor than the Epsilon is the better choice.
Designed for maximum mobility and breathability, the hooded Arcteryx Gamma SV for women is insulated in 4-way Polartec® Power Shield® High Loft softshell stretch fabric in the torso and shoulders. With exceptional heat retention in the body, Polartec&re; Power Shield® highlights the sides, arms and hood reduce bulk for fast and light traveling.
* Fabric: Polartec® Power Shield®: High Loft, Polartc® Power Shield® blends light and breathable styling with low bulk