If you don’t already keep plants, I think LED lighting has come down in price enough to make it cheaper to start plants than buy a filter and lamp for another tank. Planted tanks look terrific, but if you don’t like having your hands in there more than once a week, may not be a good investment for your time and money. Starting up plants means replacing your substrate, then futzing with light, nutrients, and gas exchange/filter output until you find the balance that keeps your plants growing faster than algae. (And the first month is usually brown everything due to a diatom bloom.)

The tank in the banner image of this community has guppy grass in the upper left corner. Other good options to look at are dwarf water lettuce (Pistia stratiotes, a plant that floats at the surface) and pearlweed (Hemianthus micranthemoides, a stem plant). Hornwort looks like extra bushy, light green pine branches. I highly recommend finding a fish or aquatic plant club locally to keep your costs down–in my area, lots of people trade and give away plants/fish/invertebrates at club meetings.