Conclusions
My hypothesis was that Energizer would last the longest in all of the devices tested. My results do support my hypothesis.
I think the tests I did went smoothly and I had no problems, except for the fact that the batteries recover some of their voltage if they are not running in something. Therefore, I had to take the measurements quickly.
An interesting future study might involve testing the batteries at different temperatures to simulate actual usage in very cold or very hot conditions.