Kingdom is really good once you get into it, though it takes awhile. I remember that I tried reading it like 5 different times and always gave up. Once it actually gets into the warfare parts though, it's really good. The characters are all interesting and well-written. There is a lot of really interesting characters in it (Ouki & Kanki) The politics part of this manga really separates itself from all the other war manga's I've read. The series focuses a lot on politics and war.
Their's an anime and a manga. I'd recommend the Manga though.
Plus you get 4+ chapters every week.