Can't really say how long I've played them, because I can't check, but anyway, most played:

Wii: Brawl, hands down. Played it way more than any other Wii game. May even have played this more than all the other games combined.

DS: Either Jump Ultimate Stars or Pokémon Diamond.

Twilight pRINCESS, Metroid Prime 3 and Lego Star Wars are the top 3
DS it's Mario Kart and Phantom Hourglass

Brawl for the Wii, easily
Metroid Pinball for DS

I too must go with Brawl. Having long since given up trying to play online, the game still beats Melee for my homemade tournaments that i'll whip up and play through if i have an hour of free time

For the DS, it is now Pokemon Pearl. I've found chasing Mesprit around to be the perfect timekiller for Airports.

Wii: Wii Sports, Twilight Princess, Galaxy, Brawl and Wario Ware.
DS: Mario Kart, Phantom Hourglass, Brain Training, NSMB and Elite Beat agents.

DS the world ends with you, while phantom hourglass closely behind
Wii: i dont hav a wii, but i borrow it b4 for a few days, i played alot of wario ware smooth moves haha

i don't have a DS but i have a wii.

Brawl, MKWii...you know all the games that never die.

DS: Mario Kart DS, New Super Mario Bros., Pokémon Diamond, Super Mario 64 DS

Wii: Super Smash Bros. Brawl, Mario Kart Wii, Super Mario Galaxy, Zelda:Twilight Princess, Wii Sports (rarely play it now however)

GBA: Yoshi's Island, Super Mario Bros. 3, Donkey Kong Country 2, Donkey Kong Country 3

1. Mario Kart Wii (unknown total, should be over 300 hours though)

2. LoZ:TP (~184 hours)

3. RE4:Wii (~183 hours)

4. Wii Sports (~108 hours)

5. Endless Ocean (~94 hours)

6. Super Mario Galaxy (~68 hours)

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Not sure what comes next, as I have played some of them since the last time I updated, but...

BWii and SSX:Blur are both somewhere between 50 and 60 hours, and Excite Truck follows at just short of 40 hours

How do you know many hours you have on RE4?

Anyway, i have
MoHH2 at over 150,
SSBB at over 190,
Zelda TP at over 90
No More Heroes for over 50
MKWii for probably 80
and so far on AC i should have about 30.