I use a glass mug at work for coffee.
It's easier to clean and doesn't add steel/paper/wax taste to my already bad free office coffee..
For getting coffee from outside, I think stainless steel mug would be my choice. Not so easy to break. And better than pastic.
I don't drink much coffee...well, don't want to get into that habit, but I drink tea. I use stainless thermo. It has lots of stain but it's OK and I don't think I'll scrub it every time. Tea stain is good....tea stained purple clay teapot is very expensive ga...LOL