Question: What's Best - Cast Iron or Stainless Steel

Answer Depends on what you're cooking.

Cast Iron:
.. Useful or can be used on a stove, oven or campfire (indoor or outdoor)
.. Best for slow cooking and roasting and when transferring from stove to oven
.. Great to sear meat and then slow cook in oven and best at retaining heat
.. It's iconic for Grandma-type baking - cobblers
.. Non-stick
.. Lasts a lifetime

Stainless Steel:
.. Popular in commercial kitchens - fast, low maintenance and lighter
.. Copper core pans heat up quickly and offers even heating
.. Best for pan sauce foods, quick searing
.. Rust-free
..(obviously) Better at 'flipping' foods like a Wok

Read:
Using Cast Ironn vs Stainless Steel and when
Cast Iron vs Stainless Steel