Would you rather know every language, but switch to a random one after each sentence, or after each year (unable to speak a different language until the following year)?

Give your answers for the following cases:

• All languages are treated equally (so equal chance for any of them to be switched to)
• Languages are weighted based on number of first-language/native speakers (so Chinese is most likely, then English, etc.)
• Languages are weighted based on number of non-first-language/non-native speakers (so English would be most likely)