Why do people favour Intel and Nvidia so much?

In my opinion, it rather helps in Nvidia's case to have better Linux driver support than AMD. That, and it seems a lot more appealing in the 3D modeling scene - just look at FaceWorks. http://www.nvidia.com/coolstuff/demos#!/lifelike-human-face-rendering

As for CPUs, mind that the AMD - especially "Bulldozer" - are major power guzzlers when it comes to power supplies. Take the AMD FX-6100's six cores taking 95W, and compare that to the i7-3770k - the highest in the power rankings, with four cores - only taking 77W. The icing on the cake is the rendering technology put on intel's chips. Sure, AMD is almost guranteed to be overclockable, but that requires an equally strong motherboard and RAM. It's much easier to play it on the safe side and get something that doesn't break the power supply, or the motherboard capacitors. That, and programs today still have barely begun to tap into octa-core processing, let alone hexa-core or  even quad-core.

The stock market is certainly paying attention to those factors - rumor has it AMD has a shot of releasing something in 2014 that can nullify these transgressions. I can't wait to see what the future would bring.