At first glance, I thought Gemini was Google Gemini

. Later, when I went to the website, I saw that it is actually an exchanger. Actually, Binance is a popular exchanger in our country. That is why Binance is more familiar to me. And yes, I am familiar with the other sites you mentioned.
And I want to tell the OP that you should trade through the exchange that is more popular in your country. Because you will get better support from it, along with more p2p sellers/buyers. Through which you can easily buy/sell dollars or cryptocurrencies.
Also i agree with programmer3666 about the security concerns.