I think 2008 was the weakest. I only enjoyed Braid out of the lineup. 2008 seems to be the most "Arcade-ish" out of the lineups. I for one am glad that XBLA is moving out of that direction. I can see many liked it that way though.
From the 2009 set Shadow Complex and Splosion Man were both really awesome. Trials HD was good too.
From this year's lineup the quality might not be as high as 2009 but in my opinion many of the games are more addicting than in previous years. I have put more hours to MNC and Castlevania than to any other SoA games so far. And of course there was Limbo which is just plain amazing.
So overall, 2009 is the winner here. It produced 2 top quality titles and one very fun one too. Then I'd put 2010 next. Limbo is just so special and MNC is one of the most fresh shooters in 360's catalog. Castlevania was a big surprise as well, it lacked in budget but made up for that in pure fun. Then 2008 for last with Braid as the only shining star there.
I didn't want to dredge this up, and you can happily ignore this part of my post if you would like, but I am curious as to how the 1200mspt across the board pricing has worked out as far as volume is concerned. How are sales compared to previous years? has anyone looked into this?
In Limbo's case, the price doesn't seem to matter. The game is already closing in to 350k sold which is really amazing. It doesn't seem to hurt Monday Night Combat either as it has been selling very well as well.
I do think the price hurts Castlevania the most. It got to ~60k sold quite fast but after that it has just stopped. I think that says that Castlevania fans bought it early but it has zero legs, mostly because of the price. Hydro Thunder is another game that would probably be selling quite a bit better with 10 bucks.
Then there is Lara Croft which hasn't been that big of a success so far but I don't think price is the main issue here. It's the fuckup with the online co-op.