Natural yarns are almost always best for wearables. It doesn’t need to be fancy (other than ooo pretty, which is my biggest criteria, too). I’d avoid 100% polyester, or high blends.

Personally, I love knitting with bamboo blends, and they’re quite affordable. They’re not suited for everything, but many feel like silk whilst wearing like cotton. And they’re often more sustainable.

It doesn’t wear as well as wool or cashmere in all contexts, but it’s affordable and very pleasant to knit with (eta: sometimes especially beginners have issues with lower end wools, which might be scratchy and which can cause friction issues in sensitive finger folds). I’d say bamboo is miles better for a beginner than polyester, and often comparably priced.