both of them are popular tho cmc is a little bit more popular than gecko but imo gecko is more accurate when it comes to coins data so many people are using it therfor ,
you can go with coingecko first and then maybe consider listing in cmc later on .
listing on these top sites may add impression to your coins but your right that it can also depend on other factors such as the usefulness or the purpose of the coin and so on ..
A recent CoinMarketCap glitch caused the service to have pricing issues. As a result, the CMC engineers identified the problem and fixed it. CoinMarketCap has a tremendous impact on any project's team, and you can't ignore that. They are clearly well on their way to establishing themselves. In terms of other crypto tracking sites, such as coingecko, the growth is still far from over. There could be some features that are attracting a lot, but it can only add to the impression, not the popularity of the site.