By "less then stellar game line up" I hope you mean when it was first released because now PS3 has not only all the multiplats but all the better exclusives. Besides Halo but I hate halo.
Really? All the "better" exclusives? The only exclusive I can think of that is worth buying a PS3 for is Little Big Planet, apart from that, the Xbox 360 really does have a better line up.
God of War 3, Metal Gear Solid 4, Heavy Rain, Beyond Two Souls , Journey, Uncharted, Infamous, Little Big Planet, Killzone, Gran Turismo 5, The Last Guardian, The Last of Us, Tales of Graces F, Valkyria Chronicles, Demon's Souls, Folklore, Flower, Twisted Metal, God of War Ascension, Sly Cooper Thieves in Time, Final Fantasy X HD, Wipeout HD.
Really? I've played almost all of them (except for The Last Guardian, The Last of Us, Tales of Graces F, Valkyria Chronicles, Demon's Souls, Folklore and Flower) and God of war is good don't get me wrong, but not really worth getting a ps3 for, Killzone on PS2 was awesome, Killzone 2 was pretty good, Killzone 3 was crap, Twisted metal isn't anything to brag about, Sly cooper again isn't really worth buying a PS3 for, Heavy Rain was interesting but not worth buying a ps3 for, Metal Gear Solid 4 was worth getting a PS3, same with Little Big Planet, Grand Turismo was great in the PS2 day (before it had any real competition) but its not quite worth getting a ps3 for, Final Fantasy HD? well that's not something to brag about at all, Wipeout is fun but again, not worth getting a whole PS3 for.
So overall, in that list, I could probably accept Killzone, Metal Gear Solid, Little Big Planet and maybe God of War as (ps3 Winners), Apart from that (and of course I can't say anything on the one's I haven't played) the others have either been done on the Xbox or something very similar.
Xbox has Halo, Forza, Crackdown, Fable, Gears of War, Ninety-Nine Nights, Ridge Racer, Saints Row (well the orginal was only ever released on Xbox anywho) and Viva Piñata that instantly spring to mind.
Overall though, between the consoles and my PC, discounting my PC I easily played more on the Xbox than I have the PS3, sure I did spend quite alot of time on Grand Turismo and God of War was a good laugh, and Little Big Planet gets played whenever I have friends round, but so does Halo. And everyone I know who come round all prefer Forza over Grand Turismo?
Conclusion? Xbox has a bigger list of decent games released compared to the PS3, cross platform games as well seem to run just as well on the Xbox (in some cases better, such as Skyrim) as well as the PS3.
As this article quite rightfully noted, the Xbox and Gamecube were more powerful beasts compared to the PS2, but it has THE biggest games catalog of any console to date and a lot of good games were made for it.
This round though, it was Microsoft's turn and the Xbox 360 has been blessed with very good titles and a decent sized catalog of games.