I just watched The Big Combo (1955) again - one of my favorite film noirs. (I talked about it earlier in this post). Fantastic cinematography, and a great cast of characters. It has a rich trove of noir themes, woven together with subtlety and skill.
One reason I like these old B-movies is that they work within a genre, with familiar situations and themes, and we usually aren't very surprised by the plot developments.