I would go for the Orca from value point of view. Orca and Onix are very comparable, same geometry and sizes. The fibers on the Orca are set in a pattern that gives the frame more stiffness then the Onix. The Onix frame is stiff enough, but is more set up for long comfy rides were the Opal is set for fast short rides, The Orca is somewhere in between.
I have the Onix with full Ultegra and FSA Compact crank, I like it a lot I don't feel the need for a stiffer bike. But for the good price I will consider upgrading to an Orca.