I've had great luck with creeping thyme and sedum, they're both super easy to care for and spread quickly. Creeping thyme is amazing because it can handle foot traffic and doesn't need much watering, plus it smells great when you walk on it. Sedum is also really tough and can survive with minimal watering, it's also great for suppressing weeds. Another option is vinca minor, it's an evergreen so it looks great year round and can thrive in shady areas with minimal care. These plants are all great for a low maintenance garden, they'll keep your space looking green and neat without needing constant attention.