I completely agree with you, I think the point is writing something personal about your niche. If your niche is making money online, then go ahead and make a personal money making blog site, in which you describe your experiences and some good ways to earn some extra cash. However I think making money online is not a good niche because there are thousands of people doing this type of blogging. Try to choose a less competitive topic.
I also think it is a good idea to create both. Consider it a test and you'll find out which one works. Hopefully they both work out