For me great graphics are those who profit the hardware potential, have a great art design to make feel the game's spirit and have a personal look and all the elements on screen are in armony in every moment. So my list...
1. Muramasa the demon blade
2. Limbo
3. Dead Space (1 or 2)
4. Super Mario Galaxy 2
5. Uncharted 2
6. Kirby's epic yarn
7. Alan Wake
8. God of war 3
9. Gears of war 2
10. Batman Arkham Assylum
Honorable mentions :
Mirror's edge (have a nice an own style, but with some repetitives elements)
Madworld (all moves so fluently and you can recognize every single thing soo well with just 2 colours on screen)