Pros: Don't stink. Comfortable
After years of wearing Polypew, I finally started wearing SmartWool tops. They're amazing. They don't stink, I could even wear one two days in a row. Try that with a synthetic top! They are as comfortable as any other fabric I've worn, do not feel like wool. Same for the socks, wear them exclusively (ultra light and light are my favorites, still have some midweights I use as well.) They stay dry and don't get smelly. PSIA members get them 1/2 price off the pro website, which is awesome.