Well a little more info... Auto patrs retailers like Autozone, Advanced, Oreilly, Main, Car Quest, NAPA etc. usually will have 2 choices of rotor in stock. I'll use autozone as an example. House brand premium aka (duralast) and house brand value aka (Valucraft). Due to the current economic structure of the world BOTH will be made in China. There may be small differences in thickness and directional finish between the 2 depending on what the company opted for. The only other difference is warranty. There will also be a 3rd party premium available for special order like brembo or beck arnley. Typically the 3rd party premiums are made in a country other than China but I can guess where their steel comes from.

The only thing i can contribute to this other than what was stated earlier about warping is that your rotor is a friction surface so that heat exchange can occur. Remeber learning about enery conversion? Your breaks are turning kenetic energy into heat energy. A thicker rotor has a higher thermal capacity and therefore can maintain you breaking performance better than a thinner rotor under heavy loads. Heat saturation = break fade