Only you can make that decision. Depends on your gear, ears, and room. By brand synergy, do you mean all the same brand cables? If that is the case, once again, it all depends on your ears, room, and gear. If you want to tweak the system, you may have more than one brand.
If, by brand synergy, you mean one particular brand of cables mating well with one brand of electronics, I think all audiophiles want synergy between cables and components.
If, by brand synergy, you mean one particular brand of cables mating well with one brand of electronics, I think all audiophiles want synergy between cables and components.