What is the best material to build this from?
Let's make a list with pros and cons with each material.
What are the main stats for this?
- Comfort (you sit on this)
- Beauty
Is this the only 2 stats?
Is it the same as bed for example?
https://rimworldwiki.com/wiki/Grand_meditation_throne
The wiki gives us a quite a good overview of the cost of this thing but doesn't give clear advice.
Do we want to base this build based on the materials? And their stats rest and beauty?
https://rimworldwiki.com/wiki/Materials
Best Answer
Material has no effect on Comfort, though quality does. (Stone has an effect on "Rest Effectiveness", which is relevant for beds, but "Comfort" is a separate statistic entirely)
Therefore the only relevant Material modifier to consider is Beauty -- which you want to maximize anyway, because part of the benefit of Meditation Thrones lies in the Impressiveness of the Throne Room it's in... which is itself a function of room Beauty and Wealth scores.
And of course, quality is a direct multiplier on material values, but because quality is not affected by material, it cancels out for comparative purposes.
(Technically hit points and flammability vary with material as well, but if you're picking throne material based on how likely it is going to take damage, some other part of your planning seems suspect)
TL;DR
Use gold if you can, and the next most-beautiful material if you can't.