I like Opal yarn- it's not particularly soft, but it knits up very nicely, and wears really well (as long as you don't go around in your stocking feet any more than necessary- but that's true of all handknit socks). I do love self-striping/patterning yarns and Opal practically invented the stuff (or was Regia first?). In the world of sock yarns, it's medium priced (around $18 per ball these days, I think I paid $15 for this) and fairly widely available (online and in yarn stores). I bought this in Portland, OR, probably at Knit Purl, 4 years ago or so, while on vacation. I knit the socks while on vacation as well (this stuff is wonderful for car-knitting. No thinking, just knitknitknitturhheelknitknitknitdecreasetoe).
I'm a bit anal about matchy matchy feet, and my stripes line up whenever I can make them do so. Opal happens to have fairly regular, if long, pattern repeats, so it's not too hard. And this stuff machine washes and dries very well. I do turn them inside out to reduce pilling, when I think of it (which isn't always).
Though I have had to darn several pairs of older Opal socks, these are not even wearing thin anywhere yet.