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 always wear as well in all contexts, but it’s affordable and pleasant to knit with. I’d say it’s miles better for a beginner than polyester, and often comparably priced.