For my first frog I got a horned frog and had nothing but frustration with it. It got stressed really easily and would just stop eating. I'm sure not all horned frogs are like this, but from what I've heard they are more easily stressed than others but are still considered a "beginners species". I would personally suggest a white's tree frog. They are large, hardy and pretty chill in temperament. They need a larger enclosure than some frogs, but they are so much fun to watch hunt!

I've never had firebelly toads, but I've also heard a lot of good things about them. They like a half land, half water set up though. It all depends on what kind of personality and set up you want