Oh the choices! I don't have just one favorite, but here are three from my top ten, in no particular order.
1. Orpington- Big and puffy with a nice, docile temperament. A good dual purpose breed, and the girls make very good mommas. The roos have been pretty even-tempered in my experience. I really like all the color varieties, but my favorite has and probably always will be Jubilee.
2. Sussex- Both of my Speckled Sussex hens have always been exceptionally curious and into things, which I really like about them. They are fair layers and just fun to have around.
3. Wyandotte- Another good dual purpose bird. Nicely tempered and beautiful, my favorite being Blue Lace Red. The hens I have are good layers, and my roo is a perfect gentleman.
A big x2 to CTKen. Your purpose for your birds also plays a heavy role in choosing breed. Best of luck to you!