Most hardy plants - What is eating mine?

I have a 30 gallon tank with the following fish:

4 - black neons
4 - zebras
1 - white tip shark catfish (small)
1 - Plecostomus  (small)
4 - gold mollies

Something has started eating my plants.  Any ideas which one?  

What is the best plant or types of plants for a community tank?  What
plants are the most hardy and easiest to grow?

Thanks!
Scott