Perhaps what you need are ideas of how to choose a domain name that can match the usefulness of the site plus have a plan to scale in order to grow beyond the limitation of current competitors.
gumtree.com, olx.com, and CraigsList.com are poor choices for domain names. This is their weakness.
None of those domain names say anything about what they do, what they offer, what benefit they give the site visitor, nothing. Zero. This is your advantage in terms of finding a domain name that can be a brand as well as plant an idea of what is in it for the site visitor.
I've never heard of the first two and the third is still a poor choice for a domain name despite that it's a brand name. It overcame it's ridiculous name by force of it's usefulness.
The domain name is important but not as important as usefulness, which relates to the "WHAT IS IN IT FOR ME" factor that aids a site in becoming popular.
What about cleverness? Craigslist is a ridiculous name. Google is a clever name. Is it important to be clever? Could Craigslist have been the next Google if it had a more clever name? No. A clever name is not key to making a site important, popular, or profitable. But it probably doesn't hurt.
But it could have been the next Google if the founder's ambition had mapped a course beyond it's roots as a place for people to find a roommate or sell their junk.
"a name for classifieds website" is extremely near sighted. Your focus is microscopic. Step back, step out of time (today, this moment), step out of where you are and step into what the situation may look like tomorrow, look at the problem from a distance. Imagine where Craigslist would be if the founder had exercised some foresight. Now you do that. The problem is bigger than the domain name.