I've tried both veg oil and goose fat and, while I do actually prefer the goose fat, there's not a huge difference.
I parboil my potatoes for 10 minutes, then add a tablespoon or so of flour to them, and bash them about by swinging the saucepan around a bit with the lid on. Then I roast them in either preheated oil or preheated fat. They're lovely either way!