1. Chrono Trigger
2. PW: Ace Attorney (I would have picked 3, but then it wouldn't have made sense without the trilogy)
3. Layton and the Curious Village (Same as above)

1. Mario and Luigi Bowsers Inside story

2. New Super Mario Bros

3. Zelda the Phantom Hourglass

Pokemon B/W
NSMB
Rhythm heaven

Pokemon
monster hunter
chrono trigger

That's a silly question, there are more then 3 Ace Attorney games!

I've picked up NSMB and I'm shopping for a Pokemon game now.

Here's my list:

1) The World Ends With You: You just HAVE to play it, not only one of the best DS games, but also one of the best games EVER made.

2) Pokemon Black or White: Undoubtedly one of the most classic RPGs out there, and B/W have the most features ever in all pokemon games. Plus if you want to get into playing pokemon competitively, this would be the best games to do so as it builds upon some very intricate gameplay mechanics.

3) Castlevania Dawn of Sorrow: Personally the game that got me into Castlevania, and a fine game at that. The sequels were very good too, but this game just had an extra charm that is unmatched.

There's a lot of "must play" games on the DS, it's probably the best software library after the SNES library, but here are my top 3 preferences:

1) Dragon Quest V - The Best DQ game ever made and my personal favourite video game story ever. I had played it before (rom emulation with translation patch), but this version is much more polished with some good bonus content added to it.

2) Pokemon Black&White - The best Pokemon games after the original Gold/Silver/Crystal from the GBC. The new battle look is pretty stylish and the new battle mechanics are also very good additions to the series. Plus it's the first pokemon game to have some sort of plot.

3) Dragon Quest IX - Not the best DQ game out there, mainly to the lack of an actual good plot in detriment of a massive focus on gameplay. The game itself is pretty massive and will last you over 200 hours, at least. The most complete DQ game out there and one of the best RPG's of this generation.

The World Ends with You, Ghost Trick, and M&L: Bowser's Inside Story.

I don't play much portables but... 2/5 of my favorite games from this gen came on it

1.Dragon Quest V. Is Just Plain Awesome (What Lestatdark said). I'm not a huge fan of dragon quest (though all the ones played are certainly good-great). But Dragon Quest V I really love.

2. The World Ends With You. The best game that I've played that best used the DS mechanics of dual screen and stylus.

3. Pokemon Black/White... it's pokemon, it's the next one. But, it's the most fun I've had with a pokemon since Gold/Silver.