Well, 'Nana' is often touted as a top romance manga. It delves deep into the emotions and relationships of the characters. The art style is also captivating.
As a fan of online literature, I don't have the ability to actually watch anime. However, based on what I know about Chinese anime, I can give you some well-received anime works such as Soul Street, Douluo Continent, Full Time Expert, One Piece, etc. These works all had their own unique styles and characteristics, and were loved by the majority of anime lovers. However, everyone's definition of good-looking was different, so the final answer might vary from person to person.
It's hard to pinpoint exactly which was the very first manga. But one of the early ones was 'Hokusai Manga' by Katsushika Hokusai. This work had a significant influence on the development of the manga style.
It's hard to say for sure. Different people might have different opinions. But some consider 'One Piece' to be one of the longest running and still ongoing.