Which of these two crude green screen lighting setups is better?
Well the 2nd is better. But the correct way is to light your Green Screen first, and you want to have it lit so it's a flat 70 IRE. You'll need a monitor with a Waveform option, and the waveform should pretty much be a flat and very thin line at 70 IRE. 

You can't do that visually (eyeballing). 

Then you place your talent so that they are separated as much from the BG as possible, casting no shadows onto it. 

Light you talent with the same color temperature light as the green screen. 

Hitting your talent with a hairlight that is gelled 1/4 magenta will help reduce edge issues.