Some things are always better in stainless or cast iron... I tend towards meats in cast iron and veggies in stainless, though it really depends.
Other things are easiest in nonstick, but can be learned in stainless, like eggs sunny-side up. Eggs overeasy without breaking the yolk is really hard though. You can do it, but it's not something you're gonna learn quick.
But there are still other things that you're basically insane to try in anything but nonstick, like thin light fish for example. Hence why professional kitchens still use lots of nonstick, even cooks who have all the technique you can have.
(And as wonderful as your cast iron patina may be, the idea that it's somehow equivalent to "nonstick" is utter nonsense. Obviously a patina is necessary, but it's not like frying eggs is ever any easier in cast iron than it is in stainless. As with stainless, any and all non-sticking is due to using lots of oil on top of a flat surface.)