I would also mention, for base layers - check out Odlo. I believe they are European and cater to skiers and back country explorers. It is a brand that REI carries. As far as socks, check out Darn Tough (another that REI carries). Darn Tough does a lot of merino wool, but, I believe they have synthetic insulated socks as well. Another brand to check out on socks is Thorlos (REI carries these, too).
I don't think you can go wrong with the REI Co-Op brand synthetic base layers as someone mentioned. Arc'teryx is great, but, expensive. If you can find Arc'teryx on sale or used, definitely go for it.