Hmm ... I believe all my choices have been said
Metal Gear Solid 4, God of War 3 , Assassin Creed Series , Farcry series , Crysis , Killzone 2, Uncharted 2
I've been sensing a lack of intelligence around lately.
Graphics's have never been a deciding factor on the purchase of a game for myself. Although they to make a big difference, I'd rather have ugly fun to play games then beautiful broken unplayable games.
Now then. my list is PC only, as i'm not the biggest console lover.
I recommend you have the latest and greatest PC hardware to play these.
Crysis Maximum Edition: FPS
World In Conflict: RTS
Company of Heroes+Expansions Tales of Valor and Opposing Fronts: RTS
(I also recommend the Eastern Front's mod for CoH, find it on the MOD DB website)
Napoleon: Total War &/or Empire: Total War: TBS/RTS Hybrid
Mass Effect 2: 3rd Person Shooter/RPG
Stalker series of PC RPG/FPS (Highly recommend you get mod's for these)
Assassin Creed 2: RPG/Adventure
Blur: Racing Sim
These are just a few of the games to come out within the last three years that are considered the "latest" graphically. Although there are hundreds of great pc games out there.