Had great results with Norma Whitetail 140 grain.
Also great results with 140 grain Accubond. Complete pass through and DRT on tough hog with Accubond.
And I expect, when I have a chance to try it, to have good results with Hornady Interlock 129 grain.
Killed a doe with 6.5 CM Norma 140 Tipstrike, very accurate in my Mauser M18; but since it was a back of the head shot, it wasn't really a good test of bullet performance.
Others I want to try in 6.5CM are HSM Sierra Gamechanger 130 and and Federal Fusion 140.
Also have some Berger 135 Classic I could try, but turning deer's innards into something that looks like it has been through a blender does not appeal to me since I know that isn't necessary to put a deer down quickly. Hornady SST does that too. But I don't like it.
Fusion has been pretty much the perfect bullet for deer in most cartridges I have hunted. They seem to have done their homework (or Speer did).