As to what is my preference: I really like all iris. The Japanese have a graceful beauty, the Louisiana's have bold color, and the bearded come in so many shapes and colors. I like a mix of new and old so you have the smooth standards and falls of the historic growing next to the fluffy newbie.
Most everyone on this site knows by now that I love the space agers especially Tom Burseens. Give me the horns and spoons and pom poms! But also give me the blends of Blyth. Throw in some flatties for more variety. Give them a gentle mix and there you have my crazy quilt of irises.