The best means literally the safest wallet used to handle and secure our bitcoin. There I used Coinbase since this hot wallet is regarded by many to be the safest Bitcoin wallet available. even though Coinbase is a digital wallet, it's quite unconventional. It's multifunctional, integrated into its market (which means that the transfer, buying and selling rates are super fast and FREE), is beginner-friendly and well-optimized.
i dont consider the best as the safest because for me both are on different category . i dont see coinbase on his list but this does not mean its not a trusted , it is but only there are people that dont like the standards of this wallet .
i didnt knew that its free to use thier coin conversion ? what about the miner fee . i havent seen a wallet so far that is free when converting/trading a coin to another coin but speed yeah they are mostly fast and instant .