Your Favorite Games to Play with Friends This Gen

[makingmusic476]

1. LittleBigPlanet!
.
.
2. Mario Kart Wii
.
.
3. New Super Mario Bros.
4. Killzone 2
5. Left 4 Dead 2

If you're talking strictly local mutiplayer, it'd be more like:

1. LittleBigPlanet
2. Mario Kart Wii
3. New Super Mario Bros.
4. Super Smash Bros. Brawl
5. Super Stardust HD

Edit:

Suppose I should also give a nod to Demon's Souls.  It's online system is definitely designed to prevent you from playing with people you know, but I've somehow managed to play that game with friends more often than most others on the above lists.