What are the best v-ray render settings for product rendering?

It depend on the project itself , is it an interior shot or exiterior one.
for example in exiteriors I prefare to use Irradiance Map as a primary bounces and brute force as a secondary bounces otherwise in interior shots I prefare using light cashe as a secondary bounces.

The most important thing is to know which settings are used for what, not to know some settings and applying it for the projects

My v-ray settings are: Image sampler = Adaptive DMC Primary Bounces = Irradiance Map HSph Sub: 20 and Interp Samples: 20 Secondary Bounces = Light Cache Subdivision: 1250 and Sample size: 0.02 and Number of Passes: 6 Use light cache for glossy rays: on and Show calculation phase: on

http://www.aversis.be/tutorials/vray/vray-20-product-studio-lighting.htm

Kindly view the tutorial

salam alikom for commercial product i use studio lightig setting whith iradiance map lightcache adaptiv DMC for lighting you can shoose between vray light or hdri lighting think you

additional to rendering settings for (product) also light settings is very important you can put the product for example a3D mobile on white area ( plan or L shape spline with curve corner to make the back is white) also put v-ray light settings: turn on -skylight portal & -store with irradiance map for a smooth shadows in same time in this case specially when you turn on -skylight portal it is very necessary to put nice vray hdri in environment map & focus on interior hdri map that make it more realistic.