1. Anubias - My personal favorite is either petite or cofferelia, but I like these because of how simple they are to grow and how much variety can be found within their genus. They make very striking images and are very sturdy plants that can be kept with almost anything in almost any conditions.
2. Glosso - My favorite carpeting plant. Give it some nutrition and good lighting, and it will cover every inch of your tank if you let it. Very pretty and classy looking plant.
3. Amazon Swords - Not often used in most aquascapes anymore, but I have a soft spot for these guys. Be them the dwarf tropica variant, the wine red aflame, or even just the big green monsters, I feel like there is a sword that can work in nearly any aquarium.
4. Hygrophilia sp. - There are a number of relatively easy stem plants and I feel like a good portion of them belong to the Hygrophilia complex. Water Wisteria, Giant Temple plant (and its many variations), Pinnatifida, and Polysperma are all great plants for nearly anyone. The things that can be done with plants from this genus are astounding.
5. Crypt sp. - There are so many different species that its not even funny. The ease of care combined with their often brilliant textures and colors appeal to both the beginner and the old timer. From the simple C. wendtii to the rarer varieties, there is something for everyone. A nutritious bottom and at least medium lighting will make any crypt happy.