In terms of tons produced, the world's most popular fruit is the tomato. There are more than 141 million tons of tomatoes produced per year, which is more than any other fruit. However, most of these tomatoes are made into tomato paste or tomato sauce and not actually eaten as a fruit.

In terms of tons produced, the next most popular fruit is the banana. There are more than 95 million tons of bananas produced per year. Next is apples, with more than 71 million tons, and oranges, with more than 67 million tons.

The mango, however, is probably cited as being the "world's most popular fruit" more than any other. There are only 35 million tons of mangoes produced per year, but it has been claimed that more mangoes are eaten worldwide than any other fruit. This is possible if the mango is lighter than the previously mentioned fruits, or if the 35 million ton number doesn't include mangoes grown for personal use, but unfortunately I haven't been able to find any numbers that actually confirm that the mango is eaten more than the fruits mentioned above.

In any case, the best answer is probably the tomato.