You can use jsut about any brand wire made for RC applications, companies like Tekin, Deans, Corally, KO Propo, Castle, etc all make it. Even the cheap brans are fine for most applications.
The key is they are all silicone wire (which makes it very flexible), and have a very high strand count, e.g. the Deans Wet Noodle I use has about 1600 individual strands!
For guage, generally 12awg is used in 1/10 brushless electric applications. You can use 14awg for 1S Lipo applications if you want (space or weight saving).