I've got SmoOth Bean 4.1.2 ver 1.5
on mine right now, it's a Jellybean 4.1.2 CyanogenMod base. Out of the box the rom is pretty good, if you've messed with rom hacking before I can give you a couple tips to make it better. It's a big change from Tap-N-Tap though, and I'm not talking the interface. It's also not as snappy as it could be, being unofficial and lacking the proper drivers to work perfectly. It's usable, but I never tried Angry Birds on it and it may not do well with that.
is another good one, based off the stock Viewsonic Froyo firmware. If you want something you won't have to mess with then this is the one I'd recommend. It'll be pretty fast and being based on stock firmware it's got all the right parts in all the right places.
This unnamed rom
is similar to the stock Viewsonic one, but a more advanced version than they ever put out. It came from a Hanspree tablet and was modded to play nice on the gtab. It's also Froyo.
edit: I realize this isn't quite what you asked for, but with the intent being to give it to a kid my opinion is a more solid or more actively developed rom would be better than a Gingerbread one.