How to pick great tattoo for lower back?

Definitely something that is personal to you. But that should be the case with any tattoo. They are permanent. Of course there is the option of having them removed but that (used to, anyway) leave scars and is, I have heard from someone who had it done, more painful than the tattoo process. So something that defines your personality is the most important.

the most important thing is that it's personal to you. especially with a location like the lower back, that is very popular with people that don't really put much thought into their tattoos (and I say this as someone with a lower back tattoo that I love) if you pick something off the wall, there's a very real risk of it looking tacky and unimaginative. I have a bat on my lower back that I designed myself, many many many years ago. and I love it. I think florals and tribals in the location can look a bit overdone. the beauty of the lower back for tattoos is that it holds up well to the aging process and you can show it or hide it as the mood takes you. a good design for the location will usually be symettrical, but can also look really nice if it's more to one side, and then up the side of the back a bit too. it's also a nice area to pick up on the natural shape of the body, and make a design that will enhance the body shape rather than mar it.