Teamspeak is good at all things voice chat, channel descriptions, channel chat, easier to navigate, more and better options to layout channels and permissions etc etc, discoed isn’t very good at that especially when it comes to plugins such as task force radio if you play arma or gspeak etc etc
Discord is good at all things text chat, teamspeak offline messages aren’t the best and aren’t a conversation, you cant have channel chats which save on teamspeak etc
It really depends on what your requirements are, most places teamspeak and discord are both essential and it’s not a case over one over the other, they are essentially different tools that have a different purpose and operation just the have the same goal of communications