Thanks for bringing live_admin to the table. We started Backpex before we released the project to GitHub, so we started with Backpex around the same time as live_admin.
We had really specific customization needs for our customers, so one reason we built Backpex was to have something under our control.
If you want to quickly add a UI for your database, live_admin seems like a good choice. However, the focus for Backpex is to be able to serve not only as an admin UI, but also as a standalone admin application that can be used by non-developers.
I haven’t looked at the latest version of live_admin in detail yet, so I can’t compare it to Backpex on a feature level, but we have detailed guides that show our features. So if you are familiar with live_admin you should be able to figure out the differences quickly.
A theme switch for our demo application is already in the works. We also worked on some user feedback, like displaying additional labels inside the filter inputs.