Exactly... Best = most appropriate for your needs, with the emphasis on your. For final renders, most people have to make a compromise between best quality and reasonable render times - unless they have a supercomputer.

But there are some rough guidelines... too many to go into all of them now, but just to touch on what works for me....

For setting up a scene layout, rough posing, lighting and camera positioning, I use a very quick render: no displacement, no smoothing, no shadows, no raytracing, pixel samples = 2 (you can even use 1 if you don't mind the edge aliasing), bucket size = 150px, minimum shading rate = 1.0 (I never go any higher than that). I saved this as a preset under the name "1 Layout".

I then have various other presets: "2 DM Shadows", "3 Raytrace minimum", "4 Interim" and "5 Final". These serve me well for most purposes, although I sometimes call up a preset and then make slight adjustments for a specific purpose.

My "5 Final" settings are not the best quality render I can get, but with my aging Core Duo iMac they represent a pretty good compromise between quality and render speed:

Smoothing on.
Use displacement on.
Cast shadows on.
Raytracing on (I almost always use raytraced shadows and AO).
Irradience caching = maximum (99 or 100).
Bucket size depends on your available memory. I use 150px for the lower render settings, and 75px for final renders.
Pixel samples = 7.
Minimum shading rate = 0 (which just means that the shading rate of each material is used).
Post-filter: your choice, but I use 1 or 2 pixel sinc. (I find that more than 2 pixels often introduces bucket-boundary artifacts on backdrop surfaces: short horizontal lines of missing or semi-transparent pixels).

For light-based AO, I generally use 9 samples. The strength, maximum distance and bias settings depend entirely on the scene content.

One final point. I always turn texture filtering OFF on ALL materials, unless I find a reason to switch it on for a specific texture. Nothing spoils fine textures so much as the default Texture Filtering setting in Poser 7 and Poser Pro, in my opinion. I have a modified SVDL script on one of my Python palette buttons which does this on the whole scene without prompting.

Hope it helps!
Izi

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)