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My favorite is Binance to buy alt coins but they don't always have what I want so I use 3 different exchanges and would open a new one if I needed to buy something different that I can't at one of my exchanges. But its safest to store your coins in wallets after you purchase them unless you plan to actively trade with them its best to keep them at the exchange.

Here are a list of top exchanges for ripple:
https://www.worldcoinindex.com/coin/ripple

Out of those I would use binance then bittrex (binance cheaper than bittrex)

I agree Binance and bittrex but I believe bittrex isn't taking anyone new at the moment. But I could be wrong things change everyday.

https://ripple.com/xrp/buy-xrp/

these are the exchanges recommended by Ripple.

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