+1 Dead Or Alive Dimensions (Lot's to unlock, good use of streetpass and spotpass, online matches- though sometimes laggy- can be great fun)
+1 Ocarina of Time 3D (for all the reasons already stated)
+1 Resident Evil- the Mercenaries 3D (though it isn't a 'proper' game, it is hideously addictive and graphically very nice)
+1 Tom Clancy's Ghost Recon Shadow Wars (Like advance wars, and despite no street/spotpass has a startling amount of longevity. Plus it's very cheap)
And the negative votes go to
-1 Pilotwings 3D(too short, impressive for as long as it lasts which turns out to be hardly any time at all)
-1 Samurai Warriors (sporadic spotpass, essentially just running about hitting buttons, AI is poor even when you tell characters what to do)
-1 Street Fighter 4 3D (nothing to unlock, online matches ruined by spammers, not much replay value)