Rewiring light fixture and switch to bring neutral line to the switch: one 12/3 switch-leg vs two 12/2 wire to bring power to switch?
I think 1 is better by far.
You mention 12/2 in the text, but the diagram shows 14/2 for the proposed option 2. What is the breaker on this circuit? Will you replace the existing switch box with an old work? The switch loop might be stapled.