Nvidia vs AMD for advanced 3D editing (photoshop, CAD, etc...)

I would have to agree, except for their tesla/quadro gpus and GTX TITAN. Unless you can afford those really nice gpus, AMD has better deals.

As for CPU Intel is best if money is no object if your on a budget get an 8350

http://www.pugetsystems.com/labs/articles/AutoDesk-AutoCAD-2014-Professional-GPU-Acceleration-504/

"From our testing, there is really only one overriding suggestion we can make when choosing a workstation card for AutoCAD: pick NVIDIA over AMD. Of course, there are still times when you would go with an AMD card (for example, you use the system for other software as well that greatly benefits from using a FirePro card) but for strictly AutoCAD use, NVIDIA is currently in the lead performance-wise..."

I'd maybe get the K2000 for about $400:
http://pcpartpicker.com/parts/video-card/#c=177

CPU?

I'd get the i5-4690K or the i5-4790K depending on the total budget as well as a suitable Z97 motherboard such as the Z97-A from Asus.

For the CPU cooler I'd get the Noctua NH-U12S or NH-U14S.

For DDR3 memory he'd probably want 16GB. I'm not sure if more serves a point.

SSD: of course you'll want an SSD such as the Samsung 840 EVO.

OS: get Windows 8.1 64-bit Pro (not Windows 7) as well as Start8.

*I was bored so I made a build you can ridicule as desired. I'll add a few comments as to why I chose the parts:
http://pcpartpicker.com/p/hptKsY

i7-4790K, Quadro K2000, 16GB DDR3 etc.

1) CPU:
The i7-4790K is a great CPU. The price going above this to a 6-core jumps up a lot. If you have the budget for a better CPU then you'll need Haswell-E likely.

2) Motherboard: Asus Z97 Gryphon
This is a "TUF" series with 5-year Warranty. It's all about quality which you want for a workstation scenario.

3) DDR3:
16GB is likely optimal. 2x8GB leaves two slots just in case more is needed (either up to 24GB or 32GB).

4) SSD:
The Samsung 840 EVO software (Samsung Magician) is really great to test, update firmware, set profile etc. I'd use the RAPID CACHE mode as well.

5) HDD:
2TB for lots of space. Good reviews on this model. For Seagate, download the free DiscWizard sofware or for WD get the Acronis True Image (same program).

*I recommend buying the full Acronis True Image software to enable automated backups and do a weekly backup (full + incremental chain which deletes the first chain once the second finishes...)

6) Case:
Nice case with two fans (I'd switch the 12cm to the front as intake). Make sure all fans are attached to motherboard and fan control software setup.

7) Quadro K2000:
For $400 it's "only" 72% of the performance of the Titan but then that card costs $1000. We're back to budget so unless render time is crucial the K2000 might be more than adequate.

8) Power Supply:
Looked for a quality supply. It's semi-modular too which cuts down on cables especially since not many will be needed.

9) Windows 8.1 Pro:
Fairly self explanatory. Improved in security, reliability, memory management etc over Windows 7. Just get START8.

10) CPU cooler:
Noctua NH-U12S. This runs silent in idle and is very quiet under load. You'll likely mainly hear the Quadro fan but unfortunately many of the Quadros have small fans for some odd reason.