My biggest fear and reason for wanting this battery is if I have little to no charge in the evening/night and can't manage to get a decent amount charged. Having a battery backup would make me feel more secure knowing I have something to keep my phone going even if I somehow end up away from a charger for an extended period of time, however irrational such a situation may be.
As such, I have been looking and found there are 3 different types of battery packs.
1) Built in Lithium ion (most common)
2) Replaceable lithium ion (ibattz mojo is the only example I can find)
3) AA based charger.
Now charger type 1 seems to be common, but overall the battery will lose charging capacity over time, not be replaceable, and will need to be tossed.
Type 2 and 3, the battery can be easily replaced, especially on the cheap. However type 2 can be smaller and slimmer, while type 3 has the benefit of using LSD NiMH batteries. For those who don't know. LSD is Low Self-Discharge in this case. A lithium ion battery dies every week or two just sitting there, LSD NiMH batteries can hold up to 75 or 85% of their charge even after a year of just sitting there.
Overall type 3 seems the most ideal. However there is another element. Some chargers have cables built in, while others have just a standard usb plug. At first I thought the USB plug was annoying and a built in cable made more sense. However after some thought, I realized the built in cables added too much bulk, and I found keychain cables, which make more sense. My favorite example of this, is the mojo treble keychain, which seems to do everything and then some.
So basically now I am looking for the best AA based charger that doesn't have any usb cable built in, just a simple full usb plug. The closest I can find is by energizer, but it has the plug built in on a super short cable that looks as if it would put undue stress on my phone if I used it.
However if anyone has any other suggestions, or reasons to recommend something else, I'd greatly appreciate any input. At this time I just want to find the most versatile option. I would also love to hear other reasons for why people went with options other than AA rechargeables for their battery packs.