Hi if you really like the crisp metal look I would go with a brushed nickel mirror but if you want to warm up space the Ikea mirrors would accomplish that as well

I agree with Elaine.

You may need to do a search for photos (at the top of this page) with white vanities and nickel fixtures. I am sure you will find thousands, a few hundred of which you will see have some warm aspect added. Just keep looking at them. See what you like and don't like in the pictures that appeal to you or leave you cold.

I did that with photos of black and white bathrooms - and there are a LOT of them, too. I looked at all styles of them until I had saturated myself with them. In my case, I needed to cure myself, since I was loving a style of tiling that was done in the Art Deco era, which was totally inappropriate for my house. I did so, and when it turns out I had the chance, I was able to do a bit of the black and white thing in our half bath. I believe that it was looking at all those pictures and thinking about how those bathrooms might relate to my own home that helped me be ready to do an appropriate version in our half bath. Maybe you would find that you really like one look - ORB with nickel or one of those ash or walnut mirrors with nickel - a whole lot more than the other. This may be the only real way to find out, look at enough bathrooms to know for sure!