The top picks not in lane to counter Varus include Nidalee, Lee Sin, and Gragas. These picks are all great at countering Varus with high win rates over 60%. Even if these Varus counter picks are not used in your lane, it's not smart to take him into any of these matchups. They will usually win against Varus.
Conversely, if the opposing team brings either Galio or Heimerdinger, you should seriously consider choosing him, as he easily wins against these champions with win rates over 54% against each ofthem.