Depends a bit on what sort of mustang.
Generally Speaking.
Vintage = Nitro
Modern = Poly / Nitro
Poly = Hard wearing. If you like a guitar that shines up niceley, even after a bit of neglect & withstands player wear & bumps. Most Likely favours the high end a bit more for a spankier sound.
Nitro = If you are using good quality timbers, as it lets the body(Timbre) shine through(breathe).If You like a guitar that will bump, scratch & show player wear, tells a story, a bit like the reliced models.
No real rules, but it might look bit odd to have a Poly finish on a Vintage project.
