TeamSpeak seems to be used by the "oldschool" & older members of the community.
The people I mostly see on the StyLis TS server are most of the staff members who have been here pretty much since the beginning & some of the veteran community members. Every now and then someone new hops on to check the place out.
Personally I prefer TS for voice chat, because, well, that's exactly what it was made for, whereas discord is just a skype killer to me. TS forces voice chat in a way, whereas discord doesn't get that much voice activity.