Puh-leez! These threads always crack me up. What's best is totally subjective. Best for what?
An SUV is "best" compared to a sub-compact car when it comes to crash tests, or a sub-compact is "best" compared to an SUV for gas mpg, it depends on what you are looking for.
The "best" A/V workstation gpu like the FireGL or Quadro is not the best for gaming. The "best" single core proc is not the best when it comes to multi-taksing. A micro-ATX case is "best" for a LAN party machine but not when it comes to a case that needs to hold multiple hard drives and ROMS.
Give me your $10K and I'll build what's best for me...
If you've got that much money to spend, just go to any retailer and buy the most expensive parts you can find...after spending that much moneuy, whatever machine you build HAS to be the best.