An artist whose works exhibit truly striking quality is Tony (also known by the name Taka Tony, his real name 田中貴之 / Takayuki Tanaka, his company RPM KK and his circle T2 Art Works); his works have come to be quite famous, and for good reason, as they are first rate, as you can see below.
Tony Taka is very much a character designer, and his output reflects that, though it is still commendably broad. His portfolio includes a variety of games, several artbooks based on those and other works (notably the Graph seires), and a variety of excellent dojinshi, though some of these are closer to being artbooks than manga.