I would say maybe a mixture of both. There are a lot of plants that are easy to take care of. If you have too much green in your tank and want some color then I guess thats when the silk plants/flowers would come in handy. I tried doing a live orchid in one of my tanks and my frog would sit on it until the leaves snapped. lesson learned I guess.
If there is a certain look you want then try some houseplants, but make sure they are not toxic (I am sure you know this precaution already)