I'm not on the road much, mostly paved/hardpack trails and use the Cateye BM-45:
https://www.cateye.com/intl/products/accessories/BM-45/

It's unobtrusive, doesn't block my peripheral vision and works for my purposes. I have it on the left side but may get another for the right. I think if I were road riding more I may take a look at the Take-A-Look.