Definately the Wii.
The DS was the market leader, and while it expanded the market heavily, it just kept its position. The real miraculous thing it did is that it sells a lot more SW than the previous handhelds (GBA had 4.5 games pr machine, DS now has 5.5 or something)
What the Wii did, was to go from being the loser of the last generation, to becomming as big a success as the DS. If the Wii hadn't taken off, Nintendo might have been pushed out of the console buisiness (as in withdrawn, as they stopped earning money on it).
The difference is:
The DS is the Ps2. It was the market leader, and went even higher, and selling even more software.
The Wii is the Ps1. It came from nowhere and took the market completely.
Of course, the DS isn't the Ps2 completely (nor the Wii the Ps1), as it did something revolutionary, but still - it was in a position to do so. The Wii wasn't.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS
