I have a Time Machine backup, but I'm going to do a clean install. My Mac dates to mid-2009, and is still running El Capitan. I might be wrong, but it feels like too much unwanted junk might come over from such an old system if I were to use Time Machine. All I really need to bring over is photos and music, which are all in the cloud anyways, plus a few hundred files, which I can take care of either via the cloud or an ethernet-to-usb-c cable.