After a horrific car crash, Dr Tenma lost his beloved son Tobio. Out of grief, he built a robotic son named Astro as a replacement; but soon after, Dr Tenma had the boy deactivated and put into a deep sleep. In the present, the scientist Dr O'Shea finds Astro and risks everything to reactivate him, train him to be a hero of justice, and raise him to be a functioning member of society. Amidst the prejudice of humanity, the pacifistic Astro will promote peace, battle the forces of injustice, and attempt to bridge the gap between humans and machines.
Black Jack is a man with god-like surgical skills. Little is known about this mysterious, unlicensed physician aside from his immense talent, which is legendary amongst the medical community; but should you require the services of this genius, you must be prepared for a hefty price tag! Though he often appears to have the demeanour of a businessman more than a doctor, Black Jack is not entirely cold-hearted; and with the help of his assistant Pinoko, he will do all in his power to save his patients, no matter how obscure, difficult or unknown the ailment. However, even a man of science like Black Jack can be surprised by the medical mysteries that nature throws at him, and sometimes even by the sheer tenacity of human nature itself.
Both of these are episodic nature, making them very easy to watch. The art style is similar (as in you can easily tell good people bad). Also, there's alot of character crossovers from Tezuka's other works in both animes.
Metropolis is a grand high-tech city-state populated by humans and robots alike. It is in these streets that Detective Shunsaku Ban and his sidekick Kenichi search for the rebel scientist Dr. Laughton who unbenounced to them, is developing a super android named Tima as a tool for the Duke of Metropolis. What starts out as a normal case turns into mayhem as the scientist is murdered, and the true plans of the Duke are finally revealed...
Both these shows were the creation of Osamu Tezuka - in fact, the original Metropolis manga produced in the 40s was a prelude to themes and philosophies he would latter develop in the wildy popular Astro Boy corpus of work.
The main (robot) protagonists, Astro (Tobio) and Tima, both have similar backgrounds: they are built as 'replacements' for lost relatives by their creators, they are both 'cutting edge' in terms of AI, blurring the line between humans and robots. Both robots were also created to serve a 'higher purpose' for their creator which serves as a central plot point.
The artstyle remains faithful to the Tezuka style, and his 'star system' (where characters are not restricted to certain series, but 'act' in multiple, unrelated stories - provide cameos if you will) is in place. Duke Red, Rock, Boon and many more of Tezuka's characters make appearances in both Metropolis and Astro Boy.
In short - same creator, same themes, same characters - subtle differences in approach and story.
*Recommendation for the 2003 Astro Boy series as this one follows Tezuka's concept more closely than the 60s and 80s series.
In the future, the net is connected to everything - from streetlights to kitchens. Each new convenience brings an opportunity for people to manipulate it. To facilitate the use of the net and to protect people from its dangers, citizens buy or create "pets". These cyber-creations not only help to find data, but also, protect them from threats. Rockman EXE revolves around a young boy, whose father has sent him a new prototype called Rockman.
I think you'd like the other anime because both are about boy robots that are constantly saving the world. There's always lots of action and shooting and flying around. So if you liked this, then you're sure to like the other.