This will depend on your location that will determine the best platform that is suitable, if coinbase is accepted in your location you can use it for trading of your cryptocurrency and for buying of any coin you are interested, over here I make use of binance because it is the best one for me and the platform is very much easier for me to understand, I only use it now to receive cryptocurrency and convert it to my bank account because I do not engage in trading again for now,, probably I may decide to go back to trading in the future. You can either make used of binance, Coinbase, luno ,bitmex depending on you and your location.