If you had to make several measurements of exactly (100)ml of water which container would you use

a beaker, an Erlenmeyer flask, or a volumetric flask would be most appropriate or would they all be equaly appropriate?

A volumetric flask is the most accurate of these three items. It is designed to hold
exactly the quantity printed on it when filled exactly to the mark on the neck.
If you use a 100-ml volumetric flask you should get the most accurate measurement.