This question has been asked multiple times on this forum and there is no one simple easy answer. While some categories perform better than others that information is irrelevant if you are unable to obtain those items at a reasonable cost that will allow you to make a net return.
It also depends on where you are selling from, what the breadth of your market is (domestic, worldwide, restricted/targeted). A lot of the items the Sri Lankan sellers list are easily obtainable at any number of B&M stores or other ecommerce sites for a lot less than what they are from the Sri Lankan sellers. Plus US buyers don't' have to worry about shipping, damage, not as described, returns, etc.
Do some market research and see if you can identify items you can acquire or make that will allow you to be competitive in the market place and still make a profit.
