First rule: Stick to brands that are well known in either optical or technology areas.
Power format, now me, I'm anti-proprietary, so it's AA NiMH all the way. The quick and cheap substitution of economical consumer NiMH beats Li-Ion for me, similarly, I prefer SD/SDHC over any other memory format.
I'd sooner drop a few megapixels for a better optical zoom. I like a good macro capability.
And I broke all my rules, my current camera, replacing my old and bulky Kodak DX3700, is a Sony Ericsson C902, a 5 megapixel cameraphone, so instead of choosing to "take the camera", it's in my pocket, and I love the "spy camera" pullout - no fiddling with menus, just pull the camera slide cover, and it jumps straight from keylock into camera ready - also one of the very few phones with a lens cover.
Could have got a phone and a better camera at the same price, but wouldn't half give me a lumpy pocket if I carried it all the time, or wouldn't have had it on me for the lone cycle wheel chained to the rack (the rest of the bike had gone!).