I usually don't knit with yarns that are heavier than worst weight. I just don't like knitting with big needles. My daughter saw a cowl pattern that called for chunky weight yarn. So I bought Rowan Big Wool. I love the spongy spring of the wool. It knit up to a soft warm cowl. I would buy Big Wool again for chunky weight projects.
A friend gave me a skein of Jitterbug 2 years ago in a color that I never would have bought. I was skeptical because I heard of the short yardage in the older skeins. I knit a sock toe up with a Cat Bordhi pattern. These are my favorite socks. They are soft and spongy to the step. I would recommend Jitterbug anytime you want a warm and comfy sock.