In my opinion, the topic that generates the most traffic is money. Everyone wants to make money online. It seems like an easy income stream, but its really not. You have to work hard before you can start generating some real income.

Another topic that is most likely to generate the most traffic is website building. Everything that has to do with website building such as making the web, getting traffic, making money with a website, choosing a topic and so on. Alot of people want to start their own websites to make money, but they don't know everything so they Google these terms so that it would help them. Just like you are doing right now, they're trying to get the most of the information you give them.

Now I am not suggesting that you should make your topic based on what I said. If you are not familiar with the topics I stated, and which is why you are reading this, you shouldn't write about that. So like I've mentioned, any topic is popular in their own way. It might not be the topic that generates the most traffic, but you will be enjoying writing on topic which you are familiar with.