If it is about Robot Anime I would probably suggest Astro Boy, I guess many people have already posted about it. Because Astro Boy is a Science Fiction series set in a futuristic world where Robots co-exist with Humans.Its focus is on the adventures of the Robot boy named as Astro. The plot consist that The Dr. Tenma's created Astro to replace his son Tobio Who died years ago, Dr. Tenma built Astro in Tobio's memory and treated Astro as lovingly as if he was the real Tobio. However, Dr. Tenma soon realized that the little robot could not fill the void of his lost son, especially given that Astro could not grow older or express human emotions.
Later When A person takes him away and makes himself the legal guardian of Astro, He finds out that Astro have some super powers with him and in the meantime he is also able to feel human emotions. Thus Astro Sets his journey to free the world from evil deeds !
Astro Boy also got many great critical response. And its probably the most famous robot anime for kids. I used to watch it too, But these days it doesn't entertain me much.