I did this for a science fair project literally over 30 years ago. The result was that the Radio Shack batteries that you got for free (they used to give 1 free battery a month) was better than Duracell.
Coincidentally enough, I judged a science fair on Saturday, and one enterprising 6th grader did the same. The results were that alkaline batteries were significantly better than other types (by about a factor of 2), and that the generic versions were slightly better than the name-brand (by about 10%).
