You should also look at the actual mAh available from each cell.

Anyway, I really wanted to standardize on AA's awhile back, due to the existence of the Lithium AA's. Unfortunately, my favorite piece of powered gear, my Petzl Zipka Plus, only takes AAA's. Now that the lithium AAA's are out, I don't worry about it anymore. I just stock both types. I just don't see the need for anything more heavy-duty, whether it's a 123 type or a D cell. I will make an exception for common coin cells, like 2032's or the like for the Photon LED lights.

So for now I have:

Petzl Zipka Plus, 3xAAA
Sony SRF-M37V radio, 1xAAA
Garmin Foretrex 101 GPS, 2xAAA
Mini Mag-Lite, 2xAA
Sony ICF-SW7600 shortwave, 4xAA
Motorola TalkAbout 6250 GMRS radios (x2) 3xAA each

and a few Photons...but that's it for electric/electronic gear for me.