Chyna.
But yeah seriously the best is silicone wire and that's hard to come by. Some speaker or audio places may have it sold as speaker wire. you can search "silicone hookup wire" on amazon for a box of whatever AWG you want.
Figuring out what AWG (width) you want is helpful too here is a chart:
https://images.app.goo.gl/6vmLuxhLcPhSKfWE8
Amazon, Ali, Bangood, maybe local hobby stores sold for other RC cars etc . Hard to find brick and mortar now days that sells what u want.
Here a link to a box like I usually buy.