Fallout 3 is impressive enough(brilliant game too), but the textures and voice work and variation in landscapes is not as impressive as Red Dead imo.
Mass Effect is impressive indeed.
GTA IV, also very impressive(as a game the world feels soulless and doesn't seem as *alive* as Read Dead's, same goes for Fallout 3, but this effect works for Fallout 3).
Orange box. Games are good but old. Dated graphics/engine, TFC 2 being an exception there.
Never played Just Cause 1/2 a great deal, have 2 on PC so might check it out.
Assassins Creed BH is relatively impressive, but I thought the game was short and the game world not as big as AC2.
From the games I have played and can remember, GTA IV and Mass Effect run closest for me, Gears of War 2 is worth a mention too I guess.
It's not always the case, but if I have a choice between two top titles, and one is on 1 disk the other 2, I'd probably go for the one on 2 disks as I'd feel I was getting more for my money. Red Dead Redemption proves to me that genius programming can turn a potential 3 disk game into 1.
My respect for Rockstar is much higher now, after the disapointment of L.A Noire and the gameplay problems(targeting, general control awkwardness) of all the GTA series imo.