The top champs outside of lane to counter Elise include Lucian, Tristana, and Sivir. These champs are all great at countering Elise with win rates over 61%. Even if these Elise counter picks are not used in your lane, it's not a good idea to play her into any of these matchups. They will likely destroy Elise.
Yet, if the opposing team brings either Kog'Maw or Ziggs, you should strongly think about choosing her, as she easily crushes these champs with win rates over 53% against each ofthem.