To be honest with you I think this is her best film, and I'm pretty sure (and don't quote me on this, I'm not 100% positive) that she said this was her favorite as well. In this she plays a recently widowed mother of two who eventually falls in love with George Brent, even if she did resist his amorous attentions at first. It causes gossip amongst her friends and in true Stanwyck style she doesn't give a damn what they say or think.
2. The Lady Eve (1941)
Her she is at her most comical and deceitful yet playful all in one. Attempting to trick a lovestruck Henry Fonda doesn't really work when she starts falling in love with him too. What makes this movie really stand out is the abundance of innuendos and last but not least a certain scene when she gets him for lack of a better phrase - hot and bothered.
3. The Bitter Tea of General Yen (1933)
Frank Capra's lesser known masterpiece which failed at the box office due to it's "interracial" relationship depicted (I quote interracial because Nils Asther who played General Yen was Danish and Swedish). If this got a Criterion release at least, it would receive the audience it rightfully deserves.
4. Double Indemnity (1944)
Forget about the wig, this is THE film noirs to end all film noirs. Her chemistry with Fred MacMurray is a huge change to the one they had in their previous movie together (Remember the Night, which is awesome). Here they are hot and then the heat starts to fizzle out when she is revealed to be nothing more than a lying, murdering good-for-nothing (insert word for a no-good-woman here).
5. Ball of Fire (1941)
In this she is Sugarpuss who takes refuge in a house of older bachelors that includes naive Gary Cooper who happens to be researching American slang. With her help she also teaches him to kiss among other things.
"I love him because he's the kind of guy who gets drunk on a glass of buttermilk, and I love the way he blushes right up over his ears. I love him because he doesn't know how to kiss, the jerk!"
There's Always Tomorrow (1956) (A Douglas Sirk masterpiece)
The Two Mrs. Carrolls (1947)