This is no easy question to answer. What’s itchy for one person is soft to another…
I’ll list some pros and cons
Usually good stitch definition, but depends on how it is spun. Works well for summer clothes or for someone who tends to be warm. Makes heavy garments, compared to other fibers. Most likely not itchy unless the recipient is allergic to the pigment. Easy to wash for the recepient. Vegan.
Stretchier to work with than cotton. Warm fiber, suitable for winter gear or people who get cold easily. Can feel scratchy, both because of allergy and because many wools are a bit rough. Merino is softer, but will not work if the itching is due to allergy. Can be trickier to wash, but there are superwash and other machine washable options. Check l
Some say it’s softer than wool, some say it’s itchy. Warm fiber, similar to sheep wool in warmth. Not as stretchy as wool so the garment will drape differently. Most likely hand wash will be needed.
Comes in soft or scratchy depending on quality. Easy to care for, comes in many colours. Not as breathable as cotton and animal fibres. Not as warm as wool/alpacka, but warmer than cotton. Vegan. Not a super sustainable fiber for the environment. Difficult to ”kill” in the wash if your recipient is not used to caring for delicate garments.
Usually not itchy. Gives some warmth but will feel cool if it’s hot. Not fun to work with if you’ve got dry hands, but the results are very nice. Needs handwash with wool detergent or silk detergent.
Bamboo or viscose
Synthetic made from cellulose that can come from bamboo, pine trees or just about anything containing cellulose. No magical bamboo properties are left after turning it to spinnable fiber, but sellers will try to lie about it. Similar to silk or cotton in that it’s good for summer garments. Usually not itchy. More lightweight than cotton. Kind of slippery yarn. Vegan.
Synthetic made from cellulose, but in a more environment friendly manner. Similar to viscose but a bit better at absorbing moisture (will absorb more moisture per weight unit). Good for summer garmens, indoor garments, sweaty people. Usually not itchy. Vegan.
Synthetic fiber made from milk. Similar properties to wool.
The yarn will have a combination of the different properties. Combine too many fiber types and the yarn will want to get pilly.
Edit: how the yarn is spun matters. Softly spun super squishy yarn will tend to get fussy and pill easier than a tightly spun yarn with longer fibers.