I would take the SACD capabilities of the Marantz......but I like SACD and am still supporting the format through classical music, where I feel that SACD is alive and well with a deep selection as well as new material coming out daily.
That said, is the Rega Apollo in the same price range?! I demoed either the Saturn or the Apollo and was impressed with the build quality all around on the Rega unit.
A newer member, timetohunt, has a thread going on the exact Rotel CDP you just mentioned.
So, if you need sacd, take the Marantz. If not, those three you listed should all be pretty equal in sound quality and build quality. I think the REGA is a step up in price and build quality........and there is the wow factor of the REGA's top loading system that looks Hot.