Plants that even I haven't killed (yet):
Small amazon swords
Banana plants (though I have had to knock the tuber cluster off a couple cause they do get icky eventually....they seem to be growing new ones now)
Java fern (which has actually calved a few 1-2" long babies for me)
NZ mini swords (I think?)
I feed them API leaf zone with every couple water changes.
Plants that I have had less luck with:
My water wisterias melt too
My moneywort mostly died off eventually, though I have a few small sprigs with some small leaves on them still.
Jury is out on:
Hornwort: Still too new, and it was in rough shape when I got it
Temple plants: One is green and looks mostly happy, one seems to be going the way of my wisterias.
Anubias: Still too new...it seems to be growing some algae and the snail is apparently being useless. The two in my "Salad bowl" seem happy