How do I get the best 5 furniture companies in US and UK?

Thomasville is one

I agree with the above answer. Plus it depends on what they are in the top 5 for. Profit, durability, output, quality, etc.

If it concerns quality, then I don't know if there is a way to determine the top 5 best ones. Some of the best ones may be only small outfits existing only in certain locations and it may not be possible to find them on any web search.

So, I would say that it is best to just go shopping around and compare how the furniture is constructed. I look for things to be sturdy, beautiful and not showing sloppy workmanship in any way.