Many commercial flocks have been bred soley to be productive,more go than show. What ever you decide it will be a compromise. If you butcher them the only real difference is that Rocks have yellow skin and Orphingtons have white skin. You won't notice this for long though as all fried chicken has brown skin. Orphingtons come in four colors Buff,White,Black and Blue.
Rocks come in seven standard colors and some others as well.
Both also have several Bantam varieties. So you have more decisions to make to settle on just one. Thats why so many of us ended up with several breeds and varieties. So many to choose from is definitly a mixed blessing. Orphingtons are probably a little more tractable,calmer Quieter natured, maybe.