Is Coinbase the cheapest place to buy and sell cryptocurrencies?

Could you elaborate on the cost-efficiency of Coinbase for buying and selling cryptocurrencies? Is Coinbase indeed the most cost-effective platform available, or are there other options that provide lower fees or better rates? Are there any hidden costs or fees that users should be aware of before trading on Coinbase? What about the liquidity and transaction speed on Coinbase - do they justify the costs involved? Is Coinbase's user interface and customer support up to the standards expected from a leading cryptocurrency exchange? Finally, are there any alternative exchanges that offer better value for money, especially for frequent traders or those dealing with large volumes?