Not sure about the impossible to kill Amazon Swords. I managed to kill one in one of my tanks. I definitely agree with Java fern and have found my Water Wisteria live through just about anything.
If you go after Cabomba later make sure your water is soft, not hard. I have hard water and my Cabomba fell apart and melted overnight with the help of my elephant ear hmpk. Depending on your lighting(I have CFLs myself) and whether or not you choose to do ferts, Alternanthera reineckii and Alternanthera lilacina seem to be pretty hard to kill (I had one in a tank with 10 watt incandescents, no ferts,no CO2 and they survived. Add 50/50 CFLs, CO2 and ferts and they're probably one of the best growing things in my tanks. However, I have read this is a finicky plant. If you get enough plants going you could also get a school of dwarf cory cats going depending on the bioload of what's already in there. In a 25 gallon you could easily host a school of 10 or so without stressing them. However you need plenty of hiding spots for them or they stress.
Last edited by Crossroads; 08-17-2014 at 03:48 PM.