I would go with a topic you actually enjoy, otherwise the whole video making process will become dull after you actually start making money, unless you plan to outsource the editing process.
Try to pick evergreen topics, something that would remain relevant months or years after you upload.
Tutorials would be good...
You can also pick up a book, something like "X - For Dummies" summarize the chapters, film some hands on examples and upload.
Story cashcow channels are also good: Horror stories, Relationship stories, Work stories, etc... But the editing process of these type of videos can turn monotonous after a while.