These two apps don't answer the same question. PlantNet answers “what is this plant?”. Floraneo answers “how do I learn to recognise them myself?”. Here's how to choose.
PlantNet is an identification app: you photograph a plant and it suggests species. Floraneo is a learning app: with lessons and quizzes, it trains you to recognise plants yourself, without needing to photograph anything.
Not for identifying an unknown plant from a photo: Floraneo doesn't do that. It meets a different need, remembering species so you no longer have to look them up. Many people use both: an identification app in the moment, Floraneo to learn.
If your goal is to learn, choose an app designed for practice, like Floraneo: progressive lessons, photo quizzes, profiles with the identification features. If you only want the name of one specific plant, an identification app is enough.