Wasn't there a thread on this already? Ah there was! In that case:
[quote name='furyk']If you're getting a system for pure emulation the PSP is probably your best bet considering you won't potentially brick the PSP by downgrading the firmware, but that has happened with the DS and DS Lite. For a pure game comparison (talking about games that are out right now only):
-PSP has much better racing and sports games. Just look at everything EA puts out and imagine a PSP version for sports plus Smackdown vs Raw 2006, Virtua Tennis, Wipeout Pure, Hot Shots Golf, Gripshift, Burnout Legends, and a host of other The DS currently has one racing game worth playing and it's name is Mario Kart. It's a little closer in terms of sports, but the DS best sports games are golf and import tennis games.
-Both are pretty equal in terms of RPGs with each system really only having one AAA title at the moment (VP:L for the PSP, Mario and Luigi: PIT for the DS). There are a couple other servicable RPGs for each system (X-Men Legends 2, Legend of Heroes series for PSP; Lost Magic, Mega Man Battle Network 5 for DS) but really you're better off sticking with a GBA if this is the only genre you're interested in.
-Unless you count Adventure games as RPGs, the DS has tons of great adventure games in Phoenix Wright: Ace Attorney, Lost in Blue, and Trace Memory. I'm pretty sure the PSP doesn't have one.
-DS has better platformers then the PSP with Castlevania DS, Super Princess Peach, NSMB, Sonic Rush, Kirby Canvas Curse, and scores of other titles. That's not to say the PSP doesn't have great platformers either as Mega Man Powered Up, Exit, and Mega Man X: Maverick Hunter are all great games.
-If you're only interested in 3D platformers, PSP wins there with Daxter alone, but it has a few other great titles with Tokobot. The DS only has Mario 64 (that's worth mentioning) and it's pretty wonky.
-Strategy games both systems are pretty equal with the PSP having Field Commander and the DS having Advanced Wars and Age of Empires
-Shooters its the PSP with SOCOM, Syphon Filter, and GTA (if you want to classify that there). The DS has Metroid Prime Hunters but that's a love it/hate it game and Resident Evil DS (which again, doesn't really deserve to be classified anywhere else).
-Mini games it's all about the DS with Brain Age, Wario Ware Touched, the Feel the Magic series, and a ton of games have mini games built in. The only PSP mini game games that I can think of is an Ape Escape game and Ultimate Block Party which both were wonky.
-Sim games, again DS. Nintendogs and Animal Crossing.
-Puzzle games with the PSP you've got a AAA title with Lumines and Lemmings. With the DS you've got Tetris, Meteos, Magnetica, Puyo Pop Fever, Pokemon Trozei, and a ton of other games.
-Fighting games its all PSP with Street Fighter Alpha 3, Tekken, Darkstalkers, and a few other great games. The only good DS fighters are imports.
-In games that sort of define being classified in any traditional genre (or that are one of a kind for each system in a current genre) you've got the Metal Gear Ac!d series, Me and My Katamari, the MGS Digital Graphic Novel, and the Gradius Collection. With the DS you've got Pac Pix, Metroid Prime Pinball, Trauma Center, Nanostray, and a bunch of other weird shit that's fun.
If you plan on importing for the PSP has the Bleach series, Suidoken I & II, Breath of Fire 3, the Naruto series, and the Sakura Taisen series. With the DS you have Jump Superstars, Bleach, the Simple series, Osu Taikae Ouendan, and Dassaigo Band Brothers. I tried to avoid picking games that have a set US release date which is why something like Loco Roco isn't listed.
The PSP is an easier system to use for multifunctionality right off the bat. The DS can play movies, ROMs, music, and browse the net too, it's just that you have to do some leg work and mod your DS to make it happen (also the cost of doing all that stuff puts it on the level of a PSP at that point). The DS can legally play GBA games but the PSP has a GBA emulator (I think) and those games are easy enough to come by. The DS has a clear advantage in battery life and durability while the PSP is a superior system in terms of graphics and hardware.
As far as future releases are concerned for the PSP you've got Ultimate Ghosts and Goblins, Loco Roco, Bomberman, Capcom Puzzle World, the Powerstone Collection, GTA: Vice City Stories, Death Jr 2, Lumines 2, Socom Bravo 2, the Eyetoy Portable, Gran Turismo Mobile, MGS Portable Ops and a Silent Hill prequel. That plus ports of a lot of the major multi-system releases.
The Nintendo DS has the following coming out in the near future. Final Fantasy 3, Contact, Mario Hoops 3 on 3, Castlevania: Portrait of Ruin, Elite Beat Agents,
Yoshi's Island 2, Kirby DS, Panzer Tactics, Phoenix Wright: And Justice For All, Pokemon Ranger, Pokemon Diamond/Pearl, Dragon Quest: Rocket Slime, Star Fox Command, Mech Assault, Mega Man ZX, Deep Labryinth, Legend of Zelda: Phantom Hourglass, and a score of sequels to GBA games.
Both systems have connectivity to their console big brothers so that may be the deciding factor. I think the DS has a stronger fall coming up then the PSP, but the PSP has the much better version of almost all of the ports coming over and it still has clear advantages in sports, shooter, and racing games. Ultimately, I love my PSP, but the $70 higher price tag and the cost of a memory stick and a Greatest Hits or other clearance title would not be worth a DS Lite and 4-8 games for me (more if you grab some on clearance). I hope this helped in your decision.[/QUOTE]
This is a few months old so some of the comparisons are a little off. The short answer is that I'd get a DS for the holidays. For a few simple reasons. I think that while the PSP has a ton of great games for it, the majority of those games can be had on a console. That's not to say there aren't games like Mega Man Powered Up, Tekken Dark Resurrection, Valkyrie Profile, Metal Gear Ac!d, and tons more that you won't love. It's just that a lot of them can be played in similar form on the PS2 whether it be as a PS1 game, off of a collection, or through a console big brother. The DS has a bunch of different titles that are somewhat distinct from the Gamecube, GBA, or N64 incarnations of their franchises. Furthermore, original franchises (to the US) like Trauma Center, Phoenix Wright, the brain games, Meteos, Nintendogs, and the Feel the Magic series are worth checking out while I believe something like Legends of Heroes or Death Jr is not.
The "new" game selection is much better for this year as the only titles I see myself buying that aren't out now for the PSP are Power Stone Collection, Work Time Fun, GTA: VCS, maybe Killzone Liberation, Metal Gear Portble Ops, and one of the many other collections coming out this year. With the DS I'll own Contact, Yoshi's Island 2, Elite Beat Agents, Final Fantasy 3, Castlevania: Portrait of Ruin, Mario vs Donkey Kong 2, Custom Robo DS, Chibi Robo DS, Clubhouse Games, Children of Mana, Magical Starsign, Kirby Squeek Squad, Pokemon Ranger, and Hotel Dusk. In terms of what's coming out for the holidays, I think the DS is the superior system on paper games wise.
So there's my huge argument. I love my PSP. I love my DS more.