GE, I don't know any other Vette models by that name, but if you mean the race-ready model then it's a no-contest... I meant road-legal production cars like Dowding says, e.g. the Z07 for the new R36 GTR, or an equivalent for the R34.
For LeMans I think that past Skylines were forced to run in RWD form.
The wannabe GT-R XYZ stuff is just japanese cultural chaff.. It's not worth paying attention to. The past GTRs' performance isn't superficial.
The inline 6 turbo sounded awesome, it's too bad they ditched it for a V6. The recent Toyota prototype spied around the Nurb sounds really good, though. Should be easy to find on youtube with "new supra".