So there is a lot of material about essays topics out there. Some good, some not so good. To reduce a very complicated subject to something simple I would say this:
you want a topic that allows the reader to get to know YOU. Don't tell them what you think they want to hear about you. Tell them about topic that is you. A topic that allows the reader to get inside your head. Tell them about your love of lock picking or your obsession with DFV wrap dresses, your collection of orchids or your obsession with Selena Gomez.
Okay, you may say, but there are lot of things that would allow the reader to know you. I love soccer; I read Michael Lewis obsessively, I love my church, etc. How do I choose between them?
Think about three elements. First, uniqueness. Second, story. Third, passion.
Uniqueness. Notice in the preceding examples the topics I suggested were somewhat unique. I didn't suggest that you should write about you love for soccer or your mission trip or volunteering abroad. Here's why. If you're an admissions officer how many times do you think I've read about a soccer team that won a key game, how your mission trip changed your life, etc. A LOT. Really, A LOT. So when I read your essay I automatically recall my favorite essay about topic X, here, let's say soccer. And the chances that your essay is going to compare favorably to that favorite essay is low. Why? Would you want to try to write the best essay about soccer out of 200 or more of your fellow peers? Never mind the hundreds, if not thousands, the officer has read in the past.
Story. So you've thought about the first point, uniqueness. But that alone is not sufficient. You also need to think about a story. Great essays tell stories that lead the reader to know something profound / interesting / take you inside the author's head. Bad essays tell you about how amazing XYZ thing is or XYZ characteristic. Given the competition you're facing you need to choose a topic that leads itself to a story.
Passion. So we've talked about uniqueness and story, the final axis on which to think about things is passion. Choose to write about something you're passionate about. Don't write about the volunteering you did, that you liked but was fine. Write about your love of Kentucky Blue grass. Write about your love of Iyengar yoga Passion comes across in essays, and passion makes your essay shine.
There is obviously more to topic selection than these three things. You need to think about how the whole package comes together, you need to think about how what you're writing about reflects the values and goals of the college. But these things are squarely in realm of college consultants or essay consultants like me. It's hard to give generic advice about that. (And besides, I need to be sure you have a reason to hire me afterall, ha.)