Katrina really only has one other suitor -- he is "Brom Bones," the nickname for Abraham Van Brunt. Other men might have liked to court Katrina, but they gave up because Brom was courting her and they were intimidated by him.
Brom Bones is essentially the opposite of Ichabod. Ichabod is a weedy, scholarly man while Brom Bones is a big, physical, uneducated country "rustic." Brom is widely known as the toughest, strongest, roughest man in the country. This is in complete contrast to Ichabod, who is clumsy and physically unimposing, but is also socially sophisticated in a way that Brom is not.
Overall, then, Ichabod is different because he is an educated man who is not really all that impressive phyiscally. He is not an outsdoorsy, "man's man." This sets him apart from people like Brom Bones.