Day 21 / 30-Day Writing Challenge
In the battle of Who versus That, That appears to be wining. Grammar purists aren't going down without a fight, though.
Who fans deride That's strategy of becoming acceptable speech through common, albeit incorrect, usage. Check out what Professor Mark J. Perry has to say.
Who refers to people. That refers to groups and things.
Example: Marilyn is the woman who is in charge of the book club that meets on Wednesday night.
Keep it simple. Keep it clean. Use Who for people, and that for groups and things.
Not to complicate matters, but That versus Which is a completely new and different battle.