How do they decide this? Well, through the games.
IGN broke it down by genres, the first of which is the action/shooter. In this category, they noted games such as Metal Gear Solid: Portable Ops, Syphon Filter: Logan's Shadow, Killzone: Liberation and GTA: Vice City Stories on the PSP, with only one mention of a DS game in Metroid Prime: Hunters. Here, they think the PSP takes the cake, but they do neglect to mention Contra 4. If you ask us, Contra 4 wins.
Gallery: Legend of Zelda: Phantom Hourglass
We now come to the fighting game genre, where IGN goes with the PSP. Titles Tekken: Dark Resurrection, The Warriors and Power Stone Collection cemented their choice, where DS games Bleach: The Blade of Fate and Viewtiful Joe: Double Trouble. What about Jump Superstars and Jump Ultimate Stars, though?
In the miscellaneous category, Phoenix Wright, Animal Crossing: Wild World and Elite Beat Agents helps the DS to take the cake. Gitaroo Man Lives! helps to put up some kind of fight for the PSP, but no dice. The DS rules here.
Interesting stuff, when it comes to the platforming genre, as IGN saw fit to deem the two a tie here. With DS games such as New Super Mario Bros. and Sonic Rush Adventure, it was enough to compete with Daxter, LocoRoco and Ratchet & Clank: Size Matters on the PSP. What the DS port of Rayman 2 though? That was a pretty good game, according to our memory.
Gallery: Puzzle Quest
The racing genre is one we're sure the DS isn't superior in, as Mario Kart DS is the only title we can honestly say deserves to be up for consideration. PSP games such as WipEout Pulse, Ridge Racer 2 and Burnout Dominator are mentioned. Having played WipEout Pulse ourselves, we're understanding of the award. And, the PSP also manages to win in the sports category, as the list of capable sports games on the DS isn't all that large. Just about every sports game on the PSP has received good marks from IGN.
Gallery: Front Mission DS
So, is this completely bogus? Valid arguments all around? Any games we, or they, forgot? What say you?