Boston Ferns are the hardiest of the indoor fern species. Maidenhair Ferns are beautiful but delicate and fragile. Rabbit foot ferns are unusual looking and do well indoors. Staghorn Ferns are super exotic looking and Birds Nest Ferns also do well indoors.
The key to success may be the available light. Most bathrooms don't have very good light, especially if the window glass is frosted. Ferns don't like direct sun, but they do require lots of bright indirect sunlight. Also, bathroom humidity is overrated unless you run the shower for most of the day!
