Hi, all! For those of you, like the OP, who have family members or friends who can't wear wool but would love handknitted socks...I am allergic to wool, so I not only can't wear it, I can't even knit with it. As a new sock knitter, I have so far tried:
CP Panda Cotton - very nice, possibly a bit bumpy on the sole of the foot, might try smaller needle (I used a US 2.5) or princess-style foot (reverse stockinette). Has only a few man-friendly colors and more coming out for Fall, I think. Bamboo, cotton & elastic. Washable, but color seems to be fading after just two washings.
CP Maizy - Corn fiber & elastic. This feels a little crunchy to the touch but makes a nice smoosy sock, according to the friend for whom I made my first pair. A bit splitty, but not unmanageable. I do recommend pointy-pointy sticks here (like KP's or maybe the Susan Bates/Boye metal dpns). Isn't fading after a couple of washings. Man-friendly colors available.
Kertzer On Your Toes Bamboo - soft and silky, really nice. Again, a bit splitty, but I guess that goes with the territory, bamboo has that reputation. It makes a super-smooshy sock, has good stitch definition, but does not come in any really man-friendly colors, IMO - a pale gray, but that's all.
Kollage Luscious - I started a sock with this...about 4-5 times...last week, and wound up taking it off the needles. I don't seem to have the right size needles for this, although I'm within the recommended size and tend to be an on-gauge knitter. It's very-very splitty, too, almost to the point of "unmanageable", IMO. But very soft and smooshy, pretty colors, but again, I can't recall any man-friendly variegateds, only a few solids that could possibly be man-friendly. The other non-wool Kollage yarns, Creamy and Corntastic, are sport, not sock weight and contain no elastic at all, so I suspect that socks would not stay up well.
Berroco Comfort Sock - I just got this, haven't knitted it up, but I've used Comfort worsted. Tends to be splitty, so again, pointy-pointy sticks recommended. It's really soft feeling, and the colorways are almost all man-friendly. Plus it's a dead-on bargain at under $8 for 447 yards, and, since it's acrylic/nylon, it ought to be very washable and resist fading.
Touched but not yet knitted - Schoeller & Stahl Sockina Cotton - not the softest cotton I've ever held in my hand, but still, wool free, with elastic, and sock weight. Not many colorways (about 1/2 dozen), but several are man-friendly. Cascade Fixation - seems a bit chunky for a sock, and rather expensive for what you are getting. I've read that elann's Esprit is essentially the same yarn, and a whole lot cheaper.
I'm sure there's more, but those are the only one's I've used or petted. If you're on ravelry, feel free to pop by my projects page to view a couple of pics of these yarns in action, bearing in mind the new knitter thing. If the socks aren't perfectly wonderful, don't blame the yarn! LOL!