English is by far the most powerful language. It is the dominant language of three G7 nations (USA, UK and Canada), and British legacy has given it a global footprint. It is the world's lingua franca. Mandarin, which ranks second, is only half as potent.
The clear winner for the easiest language to learn is Spanish. Everything from writing, grammar, and speaking will come more naturally to the English speaker: similar rules, structure, and latin roots.
The Fastest Way to Learn a New Language in 8 Simple Steps 1. Set language-learning goals. 2. Learn the “right” words. 3. Study smart. 4. Start using the language all day, every day. 5. Seek out real-life practice. 6. Learn about the culture. 7. Test yourself. 8. Have fun!