I voted an 8. For some weird reason, Nintendo tends to have really, really good E3's every four years and things are lining up to make this E3 particularly memorable.
E3 1998- Highlights: First major showcasing of Gameboy Color, Ocarina of Time, Pokemon Red and Blue, F-Zero X, Perfect Dark, Conker's 12 Tails, and Paper Mario.
E3 2002- Highlights: Super Mario Sunshine, Metroid Prime, Wind Waker, Resident Evil REmake, Viewtiful Joe, Animal Crossing, Metroid Fusion, and Eternal Darkness.
E3 2006: Highlights: First major showcasing of Wii, Super Mario Galaxy, Wii Sports, Wario Ware Smooth Moves, Metroid Prime 3, Super Smash Bros Brawl, Phantom Hourglass, and Elite Beat Agents.
E3 2010: Highlights: First major showcasing of 3DS, Kid Icarus Uprising, Donkey Country Returns, Luigi's Mansion: Dark Moon, Metroid: Other M (oh...), Golden Sun: Dark Dawn, Kirby Epic Yarn, Epic Mickey, and Skyward Sword.
E3 2014: Highlights (so far): SSB4, X, Bayonetta 2, Shin Megami Tensei X Fire Emblem (very likely), Zelda (guaranteed), Metroid (very likely), Alpha Ruby and Omega Sapphire, and Sonic Boom.
As shown, E3 this year is already setting up to be really good and these are just the games we already know about. Twitch has said that they are going to be covering four major games from Nintendo that haven't been covered yet so there are a lot of possibilities on the table. If Nintendo plays their cards right, this year's E3 could be a slamdunk for them.