The E-80 Grand Piano is quite different from G-70's one (Steinway-like vs Yamaha-like) and is same as RD-700SX "Natural Grand" sound, while G-70 is same as "Ultimate Grand" of Fantom X.

E-50/60 Piano is derived from E-80, so it is different from G-70 "Grand X".

Up to you (and to your taste) to judge which is better and why.