I just did a bit of research on Google Trends, and it doesn't really show much relevant. Even when you look on what users also searched on, it's a bit random.
If you look to your right though, you'll see in Recent Blog Posts, that Hubpages actually has a piece on finding good topics.
If you're interested in getting traffic, then rather than worry too much about which categories get the most views, you're probably better off writing about a subject you have genuine passion and knowledge about because that will create a better hub, which will lift it up teh rankings, get into the Hot area, etc. All of that will bring you more views.
The only other piece of advice is to combine "evergreen" topics, ie hubs that don't date and are always interesting, with topical ones such a recent movie review, etc, which give traffic spikes.
And lastly, look to see if you have ways to send people to your hubs, via links you may have (Twitter, etc), rather than just relying on Hubpages and Google to send you traffic.