I could say the best crypto for day trading is Ethereum. (Day trading is buying and selling of assets during the same day.)
One of the best things about ETH that makes it an ideal day trading asset is the heavy volume of trades and transactions involving it. Thousands of people buy and sell ETH every day. However, day trading takes a lot of skill and you need to be in the know about a certain cryptocurrency all the time. Nine out of 10 day traders lose money just because they are not doing their due diligence.