The Old School Otaku Lounge

Anything from Urasawa...

20th Century Boys
Monster
Pluto

There's so much more but depending on one's taste to tell you the truth.

I enjoyed "Bakuman" for it's glimpse into the manga industry, Eiichiro Oda's "One Piece" is great but there are some arcs that are not as good as others. Akira Toriyama's "Dragon Ball", "Dr. Slump" are great including his one graphic novel releases of "Cowa!" and "SandLand". I love sports manga such as "Slam Dunk", "Eyeshield 21".

I really enjoy "Evangelion" on manga.

But I can go on all day of my favorites...

A lesser-known manga that I enjoyed from a now-defunct manga publisher was Junk Force. It really could've been longer, and consequently it felt a bit rushed. At times the action seems somewhat unclear as to what is going on, but overall, It was a fun read. Only three books in the series.

Also, Crest of the Stars/Banner of the Stars, since I love that series. While most people were introduced to the series by seeing the anime on Tech TV back in the day, I was introduced through the manga. I love the art style for the first two books, but didn't care for the art style in Banner of the Stars II. There are only three books.

It's easier to recommend short series rather than long series.