Is mink what you are definitely looking for? It is definitely warm. I wouldn't buy vintage unless you need to save $$$. If you do go vintage, check the coat very carefully--make sure its not cracked or dried out, split, etc. I think you will likely prefer the feel of a new mink versus a vintage but that's not to say you couldn't find something.
Russian sable is beautiful and perhaps the highest priced (a mid-length coat can cost $20,000 or more).
Go try them on and see what you like. Mink comes in various shades and is sometimes sheered. Its all a matter of what you like.