John Willoughby and Colonel Brandon are the two gentlemen whose love interests are bestowed upon Marianne in Jane Austen's Sense and Sensibility. The reason why Marianne demonstrates an obvious partiality toward Willoughby, and it takes her forever to demonstrate any affection for Brandon, is precisely because the two men are polar opposites. In the end, however, it is obvious that looks are, indeed deceiving.
John Willoughby is a young man of a good family but with not a lot of money. He is entitled to an inheritance of property, but he demonstrates a careless attitude that, at first, fools the reader into thinking that he is just a "free-spirit". He lives with a relative at the time of his acquaintance with Marianne, whom he meets after picking her up from a fall. His debonair is that of a dandy, and his love for literature is what makes Marianne fall deeply for him. Not known to Marianne, however, Willoughby is actually not a free spirit, but a libertine. He had gotten at least one girl in trouble, one of them being related to Colonel Brandon. Always hungry for money, he makes a match with a Miss Gray, who is worth "50,000 pounds a year".
Willoughby is a shady character. He is never clear about his intentions, which leads people to pre-suppose them. This is how Marianne ends up believing that she had been in some form of engagement to Willoughby before finding out through his total disregard for her in London that she had been assuming things all along.
In comes Colonel Brandon. To the modern reader, Colonel Brandon may come across as a bit of a "perv" due to the huge age difference between himself and Marianne. In fact, he is in this 30's while Marianne is barely ending her teens when he falls for her!
Due to his many life experiences, and disappointments, he has learned to be less brash and temperamental than the libertine and immature Willoughby. While Willoughby sees Brandon as "dull" and "old", the reality is that Brandon is a measured and conventional. It is clear that Brandon has amassed quite a good fortune, and that the love that he bares for Marianne can surpass the humiliation and the rejection that she puts him through earlier during the courtship.
When Marianne becomes close to Brandon it is after she experiences deep depression and illness, and after she realizes that, throughout it all, it is Brandon who seems to always be there when she needs him the most. In the end, it is obvious that there is more than a mere infatuation; Brandon is actually a better match for Marianne because he does display the gentlemanly and mature behaviors that would complement her the most.