Know-How Exchange : Other

Here are a few idea from Google Scholar:
https://tinyurl.com/yl86y95

Brand equity is pretty broad. You'll need to narrow your thinking considerably if you want a topic that you can really address properly.

What interests you? If you're going to spend a chunk of your life working on this, it ought to be something that turns you on.

And if you have some idea about what you want to do for your career after you have your PhD, then perhaps you can pick a topic that will be useful in your career. You might as well do that as embark on a quest with a goal that doesn't matter to you.