Which Japanese word is more commonly used?

These words are interrogatives. Used to form a question in a sentence, such as why or when. (an English example-comparison) How many, how much, quantity, is the basic definition of these words. Mainly , I believe that donokurai is more in the "romanji" form of language. Used by Japanese at one time to make the language easier to understand. I'm not so sure how. Romanji is the oldest language of the Japanese, but they speak most in Kana form now. As for which one is used more often, i don't think either one is more popular. It would be like asking us which word is used more often, such as the word when, and a comparison equivalent to this word. Romanji and kana are a little confusing, but then again its like the English language, the word "gnat", why is there a g on this word? I'm sure many could question this language! hope Ive offered more help than confusion.