Which languages are easiest for English speakers to learn?

According to research done by foreign language department of US State Dept

Interesting that German is not in this group as English is essentially a Germanic language. Though it shares substantial vocabulary with the five Romance languages, they are completely distinct in terms of grammar & structure - see here.

Norwegian, Swedish & Dutch speakers of English routinely astonish natives with their facility for local idioms. Does the reverse apply when English speakers learn Nordic languages? I suspect not but would like to be corrected ...

A version of this post is included in 50 FAQ about English  ($1.75)