I doubt humidity is the problem with your anubias. I grow anubias in 2 inches of water in an open aquarium next to a window. Its in bud right now.
Possibly, its not getting enought light, or too much. Or you buried the stolon (thick stem with roots) which they do not like.
As for other suggestions, Echinodorous, Syngonium, Cryptocorynes. And there are many types of each kind.