I keep seeing alpaca and alpaca blends in knitwear but have not (knowingly) worn it before. It's llama wool isn't it??? I've always imagined it to feel wiry or rough, not that I've been that close to a llama recently...
How does it compare with merino/ shetland wool/ cashmere etc, oh ladies who know?
Alpaca is produced by alpacas which are NOT llamas but are llama-like (if you get what I mean) being specially bred to produce nice soft hair. Alpaca is a fine fibre which is hollow (like cashmere) so it is very warm for its weight and finer (in terms of "thin-ness") than wool. You can get different grades (baby alpaca, alpaca fine etc) depending on where it was taken from. Some people who are allergic to wool because of the lanolin will not be allergic to alpaca. However, IME good quality cashmere is still softer. Go into your nearest John Lewis and the knitting section may have an alpaca blend and cashmere blends - you can compare! I have a lovely hat made out of alpaca but you need to really have a feel to see if you are sensitive at all.
On different types of wool, Shetland wool is rougher and more "woolly" than merino which is specially bred to be very fine - the standard we're all used to. Remember that scratchy knitwear your gran used to knit - chances are it was Shetland wool . For nice soft knitwear, pick something like a cashmere/merino wool blend.