>I wouldn't try frying eggs in a cast iron, for instance (technically you can, but it requires an absurd amount of oil).
That's because many cast iron pans you can get these days have unpolished bottoms unlike antique ones. If you get a polished one (or polish it yourself - there's plenty of youtube videos on that) it'll be incredible non-stick. You can also just get a carbon steel pan which doesn't need polishing.