I first read Jane Austen's Sense and Sensibility in my mid-teens, and although I did prefer Elinor over Marianne to begin with, I don't think I was able to identify with either character all that much. Now that I am re-reading the novel years later, I have found that there's a lot to Elinor that I missed the first time around (also, Marianne is annoying me even more now).
At nineteen, Elinor Dashwood is the eldest of three sisters, and as such, she is expected to bear the brunt of the responsibility in the family. She's the most level-headed of everyone, including her mother, whose emotional and passionate, but altogether impractical, nature has been passed down to her daughter Marianne. Perhaps because she has been used to it for many years, Elinor shoulders her burdens without complaint. It's clear to the reader that even Austen herself thinks highly of Elinor: "Elinor, this eldest daughter whose advice was so effectual, possessed a strength of understanding and coolness of judgment which qualified her, though only nineteen, to be the counsellor of her mother...She had an excellent heart; her disposition was affectionate; and her feelings were strong; but she knew how to govern them..."
It is this last quality that distinguishes Elinor quite solidly from Marianne, who allows her feelings to govern her. Elinor, on the other hand, guards herself from relying on her gut instincts or fleeting emotions in making decisions. Even when distraught and broken-hearted, Elinor keeps her feelings to herself, partly to preserve another character's secret, but also partly because she wishes to keep her mother and sister from sharing in her troubles. Which brings me to another excellent character trait: that Elinor frequently thinks of others over herself.
This happens even with people she doesn't like all that much - for instance, Mrs. Jennings, her daughter Mrs. Parker, and the extremely reprehensible Lucy Steele. And because her sister Marianne cannot be bothered to make polite conversation with people she does not respect or care for, it often falls to Elinor to be civil to others when she, too, has no desire to converse with them. Indeed, Marianne appears to take it entirely for granted that Elinor will always be willing to fill this role (and Elinor is so forbearing and thoughtful that she does!) This also means that Elinor is forced to tell little white lies a lot of the time, although she does her best to phrase her comments as to be honest as much as possible.
Just curious - did anyone prefer Marianne?