I don’t consider myself an expert, but I’ve tried a few different NOE moulds in my 6,5x55’s.
NOE266-126 has shot very well in all my rifles, so has the NOE268-140. The 266-140 («creedmoor») has also worked well, but the two others have given slightly better results for me, I think. The 268-134 («kurz») is considered excellent for the swedish mausers, but is a bit to fat around the nose for commercial chambers, usually (mine, at least).
With ordinarily lubed bullets, sizing .266 (and .267) has worked well in all my rifles. .265 not so well. I use the NOE push through sizer, where you can get a broad selection of sizing bushings. And the .268x.264 expander plug (which fits the Lee universal flare die).
If you want to try a light weight bullet, the Arsenal 266-92 «spitzer» has also worked well for me.
Best of luck!