Hi and welcome, its not on your list but if they have the facilities and you get the chance try go give gas welding a go.
Its a nice process for sheet work and you can actually easily see the molten weld pool start to form and the rod melt as you feed it in.
Will help if you move onto tig as you can then concentrate of keeping your arc stable.
To answer your original question mig would be the best process for welding on a car, unless you are working with aluminium or building complete panels from scratch.
I've done a bit of welding when I was a boy( nearly 20years ago) I was good at tig then. But did not no if there is one to learn that is more common to use as I like making things ( not so much for a job but who knows)