Multi-game, for the sake of variety.
The best Direct moments are when we get an unexpected trailer for a new game, like with X and Hyrule Warriors.

Single are more entertaining. Multi are more exciting. Whynotboth.jpg

Probably the single, it's more focused and does a good job of building hype for specific games. The multi directs are usually bogged down with crap nobody cares about. Last multi direct they spent like 20 minutes on a F2P baseball game for 3DS.

That game is actually pretty entertaining though.

I think the Directs that have focused on only one game are simply much better! The MK8 Direct was undeniable proof of that!

I agree. Its almost like they dont care. Maybe they are betting on those nintendo fans to spread word of mouth.