Render

I think your animals and characters are all good, and the most potential for sale. I think you should try modeling some cars, if you have not already. They seem to sell good. V-ray I have never used, but I don't think it matters what type of software you use, as long as it produces good results and it enables you to export into other files suitable for other software.

Vray is good for rendering

I have never looked into it, but does Vray cost money to use?

Most render engines produce high quality, but vray it's widely used, mental ray is another one that has been used in a good extense over the years.

The good thing about mental ray is that it is included with the 3ds Max license, while Vray you have to purchase it separately.

i make low poly characters specially to be used for games so i make a high detailed texture that will stay the same or lite l deference when using any render plugin .

i use default scan-line for the characters , but mental ray and vray are both are amassing for realistic images .

i use mental ray for the commercials , fast and high quality .

hope this was helpful :)

regarding money and the cost of vray , you can download it for free

take care

Thank you all for your quick answers, they help me a lot :)

Yes Vray is good

Having vray doesn't make your renders good automatically. I've seen artist using default scanline have great renders.

Many modern renders is GPU oriented. I still use Keyshot

Vray is very good.