I've used Active Admin a few times [1]. I can't really comment on Wallaby, but AA does the job, although documentation is a bit a problem. I had to dig into the code more than a handful times to figure out the correct way to customize a certain form input. Also AA_addons[2] contains some useful custom input fields.

[1] https://github.com/activeadmin/activeadmin [2] https://github.com/platanus/activeadmin_addons