What affect more the battery time: mA or V?
The most convenient way to determine power use will be to simply multiply the voltage by the current to give power, so from lowest to highest (ignoring the equal values) we have:


1.5V x 75mA = 112.5mW
3V x 75mA = 225mW
1.5V x 150mA = 225mW
3V x 150mA = 450mW


However in practice if you want to go from 3V down to 1.5V you'll need a step-down converter, even a very efficient one will still add say 5% to the power consumed because of the quiescent current and converter efficiency so then that will change the order a little for one of the 1.5V options:


1.5V x 75mA x 1.05 = 118mW
3V x 75mA = 225mW
1.5V x 150mA x 1.05 = 236mW
3V x 150mA = 450mW


You should also check the datasheet for the coin cells you're using to check the maximum recommended discharge current. For example the table at the following site suggests that for a CR2032 even for pulsed operation 25mA is the maximum along with 5mA for continuous current.

http://www.eemb.com/Li-MnO2_battery.html