If you're looking for a NailDesignsAI alternative, starryai is a good option. This AI art generation app, which uses a prompt to create images, has an interface that's easy to understand and controls that are accessible. You can create up to 25 images per day for free, and it offers options for fine-tuning and prompt styles. The app also comes with a library of over 1000 styles, so you can use it to create a variety of artistic designs.
Another option worth considering is PicSo, which offers a text-to-image AI art generator app and online service. PicSo lets you turn text prompts into digital art in a variety of styles, including NFT art and oil paintings. It offers multiple styles, image editing and AI portrait generation, so it's good for both beginners and serious artists. The service offers a free version and a premium PRO version with more features, so you can pick the one that's right for you.