What voter i. d. policy would result in the most free and fair electoral process?

1. State-issued photo IDs. Provide them for free for those who can't afford them.

2. The system we have seems to be working nearly perfectly. Seems like about 31 cases per billion votes cast

3. The national policy for hiring new employees which requires proof of eligibility to work. There are something like 20 types of identification which can be used for this.