Yes I say do something that interests you and you have some knowledge of that subject. If you have a passion for something it is much easier to write about it and keep up dating that site. The key to the site is what is the purpose of the site? Are you going to build a list in a niche or do you intend to sell products there? You really have to know why you bought the domain name in the first place. I think you would have to tell us why you bought the site.
I have two suggestions for you. One is to do something you like, just follow your heart. so you can have the interest and passion to make it prefect. The other one is to find the profitable niche and make the website. You can think about the two suggestions on your side. Good luck.
Some people will say that finding a nich is doing what you like but you should see if what you like is more liked by people on the internet, because if it is false you won't probably have a chance to make more cash ...