The Arc'teryx system of splitting the weave on the waist/leg loops makes their harnesses VERY comfortable. I'm yet to sit in a brand that's done this as well (BD / Edelrid are both very stiff in comparison). These are not cheap.
On the whole I'd agree with this but the last generation (e.g R300) develop permanent creases in the waistbelt or legloops which makes them somewhat less comfortable. Mine will be going back to the distributors when I get round to it.
I bought a Mammut Ophir two years ago in the Dolomites when our gear got lost by easyjet. It's just as comfortable, only slightly heavier, and 1/3 the price compared with the Arcteryx.