Whenever I have a colourwork project, my go-to is Cascade. For socks, the Heritage does what the Cascade 220 does for sweaters: it's smooth, knot-free and comes in a huge array of colours. It knits up nicely with no splitting - just what you need when you need to concentrate on counting stitches and changing colours.
It's a lighter fingering weight sock yarn, but it knits up beautifully and washes well. Just don't subject it to the dryer!! Great for colorwork, too, as it comes in a bunch of colors. I am confident enough of this yarn to knit gifts to be given with pride.