This question rolls on and on! Here is the lowdown.
Titanium ASTM F-136: The standard especially for new piercings because it is lightweight (which aids healing as there is less drag) and is completely hypoallergenic. It is strong and durable. It is however, more expensive than surgical steel 316L and sometimes hard to find in more interesting designs. It also isnt as 'shiny' as surgical steel and appears a little darker. But all in all it is the premium option if you can afford it.
Titanium is better in new piercings and if you have sensitive skin or nickel allergies.
Surgical Steel 316L: Durable, strong and corrosion resistant and can be highly polished. Most people find that it is a great material to wear once your piercing has healed. Its more affordable than titanium and there are lots more interesting designs in surgical steel.
It is heavier than titanium. Its also cheaper. Surgical Steel 316L does contain tiny amounts of nickel, which can irritate highly sensitive skin. It should not be worn by anyone with a nickel allergy.
Surgical Steel 316L is fine to wear in healed piercings as long as you don't have sensitive skin or a nickel allergy.
