I know they've been all the rage for the last few years, ever since the Chicagoland Grows breeding program came out with Orange Meadowbrite. And then some Dutchman discovered the interesting double form eventually named 'Razzmatazz'. Since then, we've got the Big Sky(TM) series, the Conefections(TM) series, a couple more in the Meadowbrite series, and several more from Terra Nova.
Desipte all the hubris, my favourites remain 'Kim's Knee High', an outstanding relatively dwarf form with excellent branching, flower production and petal colour. Introduced by Niche Gardens and named for its founder Kim Hawks.
Also a favourite of mine, is the relativley new 'Green Envy', with unique green petals that eventually fade to a light pink. Some propagators have said this detracts from the plant, and have therefore been promoting another called 'Green Jewel' as one than has petals that remain green all the time. I disagree, and feel that the green petals of 'Green Envy' turning to pink are actually more unique and interesting than those that remain green.
In any case, all Echinacea (Coneflowers) are easy to grow in full sun and relatively drought tolerant once established. They do tend to self-seed a little bit, which makes the introduction of all these new hybrids into the garden, somewhat interesting.
For what's it worth, here's an interesting semi-double I found in our nursery the other day.
Here's to dirt under your nails.