Well honestly, the best can be interpreted in many ways, at a no budget just making the best computer possible at this exact moment, the following components would give you a rough area to at least start.
i7 3970X
Ram is a little harder, but 32gb would be the best you could get and speed probably would be 2400-3000 (Though 3000 speed is ridiculous in price and I doubt its that amazing)
Motherboard Asus Rampage 4 Extreme (Matter of opinion there)
4 GTX Titans would technically be the best, however for the money your spending, the scaling on the titans is not the great to the 4th card which really ruins the point of spending 4000 dollars on cards. So its opinion on this area, I would rather grab 4 7970 6gb versions or 4 780's and overclock them. But the highest score overall would be from 4 titans, so yeah (Actually, 5 titans to be crazy and have 4 SLI and one for PhysX
)
To run this setup, the PSU would have to be at least 1500Watts especially when overclocking the i7 which chugs down power. The EVGA Super Nova 1500 platinum would be the best option there.
Case: Does not matter, probably Corsair 900D or similar. That's more about space anyways, I would probably do it and build a huge water cooling system inside for all that.
4 Samsung 512gb's in Raid probably (I personally love the Samsung SSDs the most)
CD Drive, who cares? Blu-ray burner probably LG for me
Custom liquid cooling loop with swifttech parts.
That's my opinion at least