What type of topics would you be interested in for a blog/vlog?

You should blog about things that interest YOU. How can you write about something you wont be interested in.

It is you who should decide on what topic to blog about.Whatever the topic is ...try to be unique and pour in your ideas..without copying it from the internet/books.Instead of thinking about topics in which others are interested..think in what you are confident about...some may be quite confident in technology genre while some may be interested in makeup items/cooking recipes, you can also choose a blog about reviewing anything...be it a product/service/film/songs...people will definitely search for reviews before they buy the product or watch the film.Blogs relating to fashion,style,poems also has got good response from readers.So you will get many visitors for your blog.Also there are travel blogs..wherein you can narrate about the places that you visit with specifications of the boarding/travel facilities etc...There are many genres/topics to blog about..think and start with any..Keep posting and updating your blogs to attract readers...make it topic specific and blog clearly and with the correct information.It is not only the blog topic that attracts visitors it is the content, keywords that attract.Do not mislead your readers.If it is related to the recent trend then chances are there that you may get more traffic.
If you are looking for a free service to start your blog then Wordpress,Weebly,Blogger would be good.You can even get the SEV (Search Engine Visibility) service from XnYnZ.com to get good traffic.They cover many techniques like keyword and suggested topics,submit the site to over 100 search engines,submission to directories,sitemap creation and also provide reports which will eventually improve your website traffic.