I'm reading a lot right now, so I won't recommend every single thing I like and enjoy. But here is a sample:
Breaker, and Breaker/New Waves (Korean) - I love this series, the art is just getting better and better and the story is engaging. The things I don't like with series like for example Dragon Ball is that the "supernatural" stuff makes no sense whatsoever. Even though Breaker and Breaker/New Waves contain what some would deem to be "supernatural" martial arts, it all makes sense within the world the mangaka creates. It's not a complete fantasy world.
Threads of Times - Completed. It has everything, and the art is great. The mangaka debuted with this one, and won numerous prizes for it. I think it was this manga that made me actually go into manga reading because up till then I had the impression that most mangas were like all that Shouju crap you find. Thankfully, that was not the case
Berserk - no manga/anime thread is complete without someone mentioning Berserk. Really. There are anime movies based on the manga, but personally the manga can't be imitated. It's just that good.