Best Platter Material

atma,
Ive always wondered why people didnt just use an old record as a mat, if the intent is to match the impedence of vinyl. Nothing could be closer than another record, and there are certainly plenty of mitch miller or lawrence welk albums out there to make as many mats as the world could use. Maybe sand off the grooves so it is perfectly flat and then bond to the platter.

I think the alumimum/lead sandwich of the VPI TNT made an excellent platter, but the platter interface with the record is a different story. for that I use and recommend Delrin, which is also my second place choice for the entire platter.
You are asking for two different things. One, which material makes the best platter and two, which material interfaces best with the record. The answer to those questions are likely two different materials, as I stated above.

So, instead of ascribing some nefarious motive to VPI and others, why isnt this just a case of a manufacturer trying things to see what works best and a certain price level. It is much easier to machine or cast an acrylic platter than a 2" thick aluminum one. And I'm sure VPI's multi laminate lead platter was expensive to manufacture. Transrotor uses mainly aluminum on their better tables. Look at Teres, they went from acrylic to wood to delrin. Was that just to sell more, or was it an attempt to see what works better, for most people, most of the time, on most systems.
I dont have a turntable with an acrylic platter, but they looked nice and shiny at the time they were in vogue, brought on mostly by the Clearaudio Statement, and the theory of matched impedence seemed reasonable. Now we have moved on.
Not everything is a conspiracy by business to screw you.