Well because English is essentially a Germanic language, the closest languages there are to English are other Germanic languages such as German and Dutch. Example: English: Hi! My name is Madie. I am nineteen and I live in California. German: Hallo! Meine Name ist Madie. Ich bin neunzehn und ich wohne in Kalifornien. Dutch: Hallo! Mijn naam is Madie. Ik ben negentien en ik woon in Californië.

I think Scots, if you do take/consider this as an extra language... Then it will be Frisian, a minority language in the Netherlands. After this, I assume that Dutch is the closest... But French has a great deal of common vocabulary with English too, because of the heavy Anglo-Norman French and Latin influence... Also I think that the Scandinavian languages have, perhaps the most(?), comparable grammar with English...