From the point of view of not releasing microplastics into the environment/not supporting the plastics industry I try to avoid synthetic fabrics as much as possible.
You might find cashmere and possibly merino aren't itchy OP. I have trouble with other wool though I can manage merino if I wear something thick under it. Cashmere can make me itchy at times too, and I usually wear something under cashmere too as I don't want to be washing it much. Merino can go in the machine no problem.
There are ethical considerations about natural fibres too though - the one I haven't seen much about is linen. Everything from pesticides, water usage and slave labour apply to cotton.
I have a viscose top I think from Hobbs my DM gave me years ago that looks really well, is soft and comfortable, hasn't faded or developed balls, despite much wear and abuse and washing even at 60 from time to time.