I own items multiple items from smartwool, ibex and icebreaker - though only ibex jerseys.

I would say:

Ibex is the highest quality and most comfortable. Mid-price, though I've never paid full retail. The current Ibex sale, though Feb 2nd is the best deal I've ever seen on their stuff. I purchased two extra jerseys to hold in reserve.

Icebreaker has the best style, holds up well, but is sometimes a little scratchier than Ibex. Most expensive too. The upside is that if you wear a large, you can find dealer samples on the net for considerably less than retail. They are currently having a 43% off sale through 5pm today.

Smartwool has the best distribution and is the cheapest. I prefer the other brands though, and wouldn't buy smartwool again.

Also, the Defeet Wool Blaze sock is my year-round sock. Gets ridden in five or six days a week, and like all my wool only gets washed about once a week.