Being a dart frog hobbyist, I use ABG or similar derivative under a solid layer of sand oak and magnolia leaf litter. It's a precise mix of orchid bark, peat moss, charcoal, sphagnum moss and tree fern fiber. The reasons are ABG is excellent at supporting microfauna and excellent drainage with enough water retention to support tropical plants. The variation in leaves is due to magnolia leaves breaking down faster than sand oak providing both long and short term food for the 4 different isopods and 3 different populations of springtails in my tanks.
heres the recipe for it but it can be bought premade. It's only cost effective to mix yourself if you're going to fill a lot of tanks. Otherwise, Josh's, ne herp and lots of other retailers sell it in one gallon premade bags.
2 parts Ground Tree Fern Root
2 parts milled Sphagnum Moss
2 part orchid bark
1 part sphagnum peat moss
1 part charcoal