Or, when all is said an done, you might just take MikeS’ list, or another technique aiming to find the compact shapes, and simply go through eyeballing an them and throwing out any that are subjectively too “pointy”, “indented” or “straight-lined”. On that basis, my vote goes to Nauru.
Technically, it doesn’t “contain” the data, in the sense of it being part of the local software installation. Instead, it has functions that, when you call them, contact Wolfram’s servers and retrieve the data you ask for. (This has the advantage that the data is up to date so long as Wolfram keeps updating it, but does have the disadvantage that you’re “tethered” to the internet and to the whims of Wolfram.)
I just want to say that this thread represents the SDMB at its finest. I’m proud of each and every one of you. 