I bounce back and forth between synthetics and wool. I always prefer wool, but sometimes I go with polyester/nylon because I know it's somewhat of a task to wash the wool after I get home from a trip.
Generally speaking, if you want to keep any of your outdoor clothing in tip top shape, use the right type of cleaning agent. Avoid the majority of stuff at the supermarket. Most detergents leave behind residue so it'll clog up and gunk up the material, resulting in less breathability, less wicking properties, less water repellency etc. So again, avoid woolite. Some use simple soap flakes, to avoid all the extra stuff that comes with detergent. A lot of other people buy nikwax brand stuff, but its way too expensive for what it is. Hence, I tried to go with the revivex concentrate which gives me more loads per bottle. I'm hoping that atsko sportswash will be my do-it-all cleaner because its so cheap, and readily available (via amazon)