Astro Boy wins. Not only was it the first anime TV series, it established most of the classic themes and tropes most people think came from DB.
Pure-hearted, innocent hero fighting to protect Earth? Check.
Power levels? Astro and other robots measured theirs in "horsepower."
Bad guys who become good after getting beaten by the hero? It happened several times, most notably with Astro's creator, Dr. Tenma.
The old "hero gets owned by mega-powerful villain, powers up, comes back and beats him?" storyline? Yep. A robot named Pluto nearly kills Astro, so he powers up from 100,000 to 1,000,000 horsepower and beats him in the rematch.
Several smaller robots combining to form one big superbot? Astro had a couple of stories with that.