It's difficult to judge given that it's MP vs SP and we saw a wider variety of environments in Ghost Recon but yeah having just re-watched both on the big screen I'd put them about even I think. But then if it's truly open world then that could be a feather in GR's cap. Either way I'll probably be getting both, plus the new NFS which between them showed the best multi platform graphics I've seen so far from E3 (I've seen 1 or two very good looking exclusives too but I'm excluding those to keep things on an even keel!).
EDIT: Ghost Recon also seemed to have a few aliasing issues, I wonder if it was running on PC of PS4? Given they didn't specify I'd assume PC but based on image quality in some parts I'd have said PS4. If it was PC then the game may not yet have any advanced AA modes built in - I hope that changes before launch.