Also depends on where you're driving and also how far from civilisation (fuel, food, water, help) you are going.
An example for me is that I mainly do day trips close to home in areas that my friends know well and usually in phone reception so if something bad happens I can get help quick.
In tassie you're never far from water either.
In contrast, it is completely different if you're going deep into isolated desert areas with no help, no water, no food, no fuel close by.
So if you work out where (and what conditions) you're going to be driving in mostly then you can work out what gear you really cant do without.
Also, as has been mentioned, all the gear in the world is no good unless you are competent in using it so practice before you have to rely on it