The highest award a Sigma Kappa chapter can win is Three Stars in the Standards of Excellence program. It is given to chapters who excel in a wide variety of areas including sisterhood, academics, programming, Panhellenic relations, recruitment, leadership, etc. It's not so much of a competition among chapters, but just chapters challenging themselves. Theoretically, every chapter COULD get three stars since there are outlined criteria (far above minimum standards) of what a chapter must achieve to get the award.
There were 11 Three Star chapters last year:
Alpha Sigma, Westminster College (PA)
Alpha Chi, Georgetown College (KY)
Beta Zeta, University of Maryland
Delta Chi, University of Central Oklahoma
Epsilon Delta, Susquehanna University (PA)
Epsilon Tau, California State University, Fullerton
Epsilon Chi, Virginia Tech
Theta Zeta, University of Virginia
Theta Theta, Albright College (PA)
Kappa Zeta, Elon University (NC)
Kappa Iota, University of Pennsylvania
There are other awards that include one chapter as the best in a specific category, and a few (3-5) honorable mentions. Plus, there are recognition awards for sisterhood (19 chapters recognized) and academic achievement (36 chapters recgonized).
Beta Zeta, University of Maryland won more of these awards/honorable mentions than any other Sigma Kappa chapter

, including:
Best Public Relations
Honorable Mention for Excellence in Recruitment
Honorable Mention for Outstanding Implementation of the Promise Program (Our NM program)
Honorable Mention for Best Member Development Programming
Sisterhood Recognition Award
Academic Achievement Award
I really don't think I am being biased when I say my chapter is awesome.