THere's more to this than amd v intel. 

Consider a simple formula.  cores x speed.  Intel can double the cores.  Vue sees the virtual cores.  So if you have, for example, a xeon processor (or an I7), double your cores. 

Lets say you have 6 actual cores in a xeon or I7.  Vue will use the virtual cores and will see 12. 

Now speed is also a factor for Vue.  6 cores at 2ghz is the same as 3 cores at 4ghz.

So cores x speed = render factor.

Now I have been away from AMD for awhile. If AMD can offer virtual cores, great.  I thought I saw an AMD processor that claimed triple cores (double virtual cores), but not sure about that. 

I run a dual xeon rig.  2 CPU's that are 6 core and 2.6 ghz.  6x2=12 actual x2=24 total x 2.6 = 62.4 for a render index

A friend bought an I7 6 core that runs at 3.5ghz.  6x2x3.5=42.  That is pretty fast. 

We're talking Vue here.  Bryce only uses 8 actual cores at 80 percent (sort of). 

So a render index of 42 is about 67 percent of a render index of 62.4.  Consider cost.

Take the cost of the computer and divide it into the render index. 

I got a gonga deal.  I spent $4k on my machine.  She spent 3K. 

She is at the top of the line for her I7 machine, but that's fine, she doesn't need expandability.  She has a cost/render index of 0.14 ($3k / 42).  I have a cost/index of 0.156.   In essence, she is paying 14 cents on the dollar for her machine and I'm paying about 16 cents on the dollar.  The sole reason for my build was that one of these days I plan on going to high speed 8 core CPU's and all I have to do is pay and plug them in.  She has to build a new machine and load everything. 

This works for poser and Terragen 2 and DAZ Studio.  It does not work for older software like Bryce or Terragen 0.93.  (those softwares can only see a few cores, not all). 

It also does not work for GPU renderers like luxrender, reality or octane.  Those need lots of cuda cores on GPU cards.

Hope this helps.   I did a lot of testing during renders in various apps using resmon and argus and gpushark.