Determining the "toughest" languages for English speakers to learn can be subjective and depends on various factors such as linguistic distance, grammatical complexity, writing system, and cultural differences. However, based on general consensus and linguistic research, here are 15 languages often considered among the most challenging for English speakers to learn:
1. Mandarin Chinese2. Arabic3. Japanese4. Korean5. Cantonese6. Icelandic7. Finnish8. Hungarian9. Russian10. Navajo11. Georgian12. Thai13. Vietnamese14. Polish15. Czech
It's important to note that this list is not exhaustive, and individual experiences with language learning can vary greatly. Additionally, a language's difficulty can be influenced by personal factors such as motivation, access to resources, and prior language learning experience.