Sorry for the late answer, sadly this site isn't as active as it used to be Both darts and firebellies need nigh humidity, although I believe firebellies need a little more ventilation. A glass lid should work for both, just make sure to drill several holes for ventilation. There are some dedicated dart frog forums you may be able to find with a little research.

IMO, with that big of a tank I would go with darts due to how outgoing they will be. And while you will definitely need to do some regular maintenance it definitely won't be anywhere as bad as maintaining an aquarium.

Enjoy your future froggies!