There are many online exchangers where users can buy or exchange cryptocurrency. To choose the best conditions for yourself, you can use the BestChange service. Here you can find information from more than 440 exchangers. Here you can quickly find offers of different exchanges for buy ripple https://www.bestchange.com/visa-mastercard-usd-to-ripple.html and for buying other cryptocurrencies.
Ohh. I can recommaned you the baest pair of the most reliable crypto exchanges - gemini & coinbase. You can read by yourselfis gemini better than coinbase here
