No down time due to waiting for air makes the angle grinder a no brainer.

I've used them on all my suspension components to get off old rust/paint/gunk and I was able to do parts extremely fast. Just make sure you hold on and wear that thick clothing that demacoz mentioned, I've also fallen victim to that.

You can get different types of wire wheel too, have a go with a couple of different types to find one that suits your needs.