Speaking from experience - I'm new to this, and anything that stays alive in my tank, I'd consider 'extremely easy'.
The aformentioned Java fern, couldn't be easier, and attractive, too. Make sure to tie it to a rock or wood, don't bury it.
Urticullaria graminofolia, called mouse's ear over here - never see this plant getting any love online! It's one of the nicest plants I've had, with beautifully shaped leaves. Seems extremely hardy, and small fish seem to love the shade it creates, and create mini territories where leaves overlap and make semi- enclosed spaces above ground level. It even stayed alive in my axolotl's 16 degree celcius tank, left floating, with about 20 mins of window light a day, for months! Grew roots and clung to the filter intake in the top corner, haha.
I never see anubias over here in NZ, maybe Mouse's ear is our equivalent easy broad leaf plant. I love it!
Personally I'd stay away from java moss, looks a bit yuck in lower lighting, and almost always ends up, bit by bit, inside the filter, clogging the impellor. I've never been able to convince it to grow tied onto wood, rather than float away on the current. I guess it's free-spirited
Also temple plant, grows fast, and tall if the light is low. Bushier if light is higher. Looks lush, and being fast growing, helps discourage algae.