I can tell you that GTA IV and GTA V both got 10s. In the case of GTA IV, there was controversy because some people thought the review didn't point to a "10". Honestly, I can't believe anyone gave GTA IV a 10, much less a publication where earning a 10 is supposed to be a rare event. RDR1 got a 9, which is kind of amusing to me, as EDGE is supposedly all about gameplay and RDR1 was mediocre at best in that regard.
Personally, I would have been shocked if RDR2 didn't get a 10 from EDGE and I mean that in all seriousness.
so it seems we will not see a 10 review from edge a long time