Check out Maximus Arcade. It's an OK front end, fairly basic, but easy to set up and navigate. It's difficult to add non-supported emulators. It lacks support by the developer and the community is quite small.
Now, if you don't mind a bit of setup, and your romsets are named using No-Intro naming convention, then HyperSpin is highly recommended. It is easy to setup if romsets are named correctly. It looks great and the kids tend to love it. Once setup you can't mess it up unless you have access to the config application which is not accessible via the front end. You can create a HyperSpin theme that displays any artwork file as long as it's png format.