Can't tell you what's best, you can really only do that yourself by looking into the specs and the performance that real users are actually getting from the various components.  I can give you my personalopinion, but those using other brands probably won't agree.

When I built my current system, I was lucky enough to use Amazon, and the good thing about that is you get to flush-out the crap and hang onto the good through trial and error.

All I'll say is that two things became very obvious to me regards quality after a lot of messing and swapping around of components.  If "quality" is important to you, I recommend you stick to ASUS components absolutely everywhere possible.  My motherboard, graphics cards, soundcard, and monitor are all ASUS and every one of them are well designed, quality products - even the packaging for them is a quality affair (even better packaging than Apple in most cases).

As for the processor, AMD or Intel?

Again, I went for quality.  I personally think the AMD processors are physically better built than the Intel processors and the AMD stock cooler totally blows the Intel effort into oblivion (at least this was the case when I built my current macine).  That said, I think the Intel is probably a better 'performance' processor - although not by much - and at a lot more expense.

So basically, I started by building an ASRock/Gigabyte/Intel machine but ended up only being satisfied with an all ASUS/AMD machine.  I'm happy, it feels every bit as fast as the Intel build did, it's absolutely way better quality, and amazingly quiet for what is really quite a powerful machine even by todays standards.

As for rendering machine basics; I'd go for as high a clock speed and as many cores as you could afford.  Get a sensible amount of RAM, and if you plan to do any GPU-based rendering using Octane, you'll need an nVidia-based card with as many CUDA cores as possible.

Hope that helps!