I know what you mean about Colt. But to me, they will always hold a spot near the top simply because of the materials used and because they are held to a known standard.
Sionics is a small company, building a great gun. They've actually made some Department sales here in the Atlanta area. Sandy Springs and APD, I beleive. I know their master armorer and he is one of the most knowledgeable AR guys I've ever met. The guns are solid, quality parts and well made.