I've got one finished so far:
I'm using Bernat Sox in Wooded Denim, it's an acrylic/nylon mix. Although I did read a bad review, I think it's just fine. It's soft (not Panda Cotton soft, but still soft), sturdy, nice colours. Admittedly it's not that elastic, but I think it's okay for me. I haven't washed it yet, but from trying it on as is, it's great.
I also love the Spring Forward pattern. I'm using 2.75mm needles and changed the ribbing a bit.