So would Kraken, Binance, Coinbase Pro be considered secure and reputable sites to buy crypto?
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The three exchanges you mentioned are, indeed, one of the most reputable and secure platforms.
Security is a relative concept, though.Centralized exchanges, usually, charge flat withdrawal fees and it's a bit higher than what most fee estimators would suggest.
My advice is to use a reputable exchange and pay higher fees than risking all your money with a new one just to save few bucks.