Turntable Mats for Technics Grand Class, "G" Series

I like Boston Audio graphite mat on my SP10 mk3. BA don’t make it any more but someone else does. Sakura????

I've got a 1200G and I use a Stein Music 'The Perfect Interface' Pi mat. It's the only mat I've ever used on it, and it sounds excellent. Might have sounded just as excellent with something less expensive, but I'm happy. 

I also use Boston Audio graphite mat on my SP10 MkII, I purchased mine from Sakura.

I also have a GAE bought when they were introduced and like you have replaced the OEM mat.  In my case: leather, acrylic, Herbies, Origin Live (favored for years) and recently the new Origin Live Strata.  The Strata is magic.  Really.  Expensive (295 pounds sterling), but worth it and it has a return privilege if you are not satisfied.  One word of caution, Origin sells the Stata in a slightly smaller diameter version specifically for all SL1200 turntables.  Since I also bought a Strata for my HW40 in the standard size, I tried both sizes and much prefer the standard size mat.  The smaller mat just looks funny to me on the GAE.  Same price, same sound, just an aesthetic thing.