I think it honestly depends on how big is your tank, what are your lighting requirements/that you have, and also are you looking for some more background coverage plants that match yours already? Do you have any decorations that you are trying to place plants around with?
It really depends on the size of your tank and how much time you have to put in to take care of a plant. I know that Java Moss is one of the easiest to take care of and grow and is great for beginners who are just starting out growing plants in a tank. This is great as a foreground plant in the aquarium.