I agree with pretty much everything that was mentioned above. One thing that I would like to note is that it is amazing how under appreciated the N64 was considering it has at least 5 games that come to mind that rank as some of the greatest games of all time and it didn't have anything even close on the competition during its generation. (mario 64, goldeneye, Ocarina, Banjo, Perfect Dark)
If I limit it to this generation. The first year I had the 360 Gears of war 1 blew me away to where I couldn't put it down for months. The story was adequate, but the game play and level design was in a world of its own. Then the following year the first Bioshock game came out. The imagination and the originality of the storyline makes it one of the best games of all time. The first Assassins Creed game would also make my list. Its too bad the sequels of all three of those games were pretty much just lesser efforts clones of the originals that didn't add much of anything new.
Did you just claim Assassins Creed was better than its sequel. Assassin's Creed 2 is the superior game so says everyone.
My best single player experience probably Mass Effect 1 & 2. Which I am including as one game because i played the two very close to each other also decisions in the first game carry over to the second. Now why is it my best single player experience firstly because they are many different ways to do levels which is one of the best things about interactive storytelling. Also the gameplay in the 2nd one (the superior of the two games) is very good almost as good as other third person shooters such as Gears.