I'd say the best hubs to write are things you feel most passionate about.
You should write for yourself. Don't chase the money. If you only look to what you think will bring in money, you will become disillusioned very quickly.
Believe me I have seen some good talented writers chase money an burn out in weeks, disappointed in results.
Concentrate on writing strong content, share experiences, give tips, become an active member of the community and you will find success.
Take time to build your portfolio of work, it can take years of work, you will not make a lot of money quickly anywhere on the web. Slow, steady growth and in a few years you will see a good return for all your work.