Crypto market is go down in this movement. I have some USDTs. So I want buy some coins. Is this time good for buy? What are the good coins to buy and Hole long term? Any suggestions? 
The best choice will always be Bitcoin and Ethereum because they are the most promining and have the most potential to make your money to grow that even in the moment like this in which still the bearish market is in effect they still lead all coins in talking of price and market performances.