Best cast?

Curious what everyone’s favorite group of main cast members for a season were? For me it was the season 5-9 period, but especially when Dr. Warner, Dr. Wong, and Casey Novak were main cast members. I always thought Casey was removed from the show far too soon (not that she had to ever be removed, but 5 seasons was far too short). 9 was a good cast, but I felt Adam Beach always seem as an unnecessary addition to that cast.