Write what comes from your heart. Write what interests you. Hubpages is a community of writers, and you will find friends and mentors who enjoy writing and reading the same topics that you do.
You never know who you will touch with your craft. If you make one person smile, or learn something they find useful, you are successful.
If you find that you have writer's block, just stop thinking about it and do something different for a while. It never hurts to ask others what they would like to learn about, either. I like topics regarding inspiration, health and productivity, animals, history and genealogy. Others will like to read about sports or politics. The most important topic to write about is the one YOU want to learn about and read.
Good luck ~