I was thinking of getting one of them but I'm not sure which. Can anyone tell me which one is better and why.

It's all about preference. What are you looking for from a portable? If you like on the go games, quick pick up, no load times, fast and fun, a DS Lite might be the best choice. If you want console games on the go, you'll want a PSP. If you want to also listen to audio and watch videos/movies, you'll want the PSP. And if you want a highly customizable/hackable platform, you'll want the PSP.

The DS is highly customizable/hackable too(Supercard). You can also listen to audio and watch videos(moonshell)(but I would recommend the PSP for videos alone)

You have to look at the games and features and make that decision for yourself.

Pros of PSP

1. decent games

2.Better graphics

3.plays other media (movies, music)

4.Big Screen

5.PS3 Compatible

6. Surf the internet

7.Good Online

Cons Of PSP

1.anoluge nub?

2.not long battery life ( compared to the ds)

3.decently big

4.screen scratches easily (without a cover)

Pros of DS

1.Good Games

2.Touch screen

3.Long Battery Life

4.Closes so you dont have to worry bout the screen

5.GBA Games Compatible

6.Wii Compatible

7. Will Surf the web

8. Microphone

Cons Of DS

1.Not Every1 Likes the DS Touchscreen

2.Bad Online

3.Doesnt play movies, music (who cares?)

4.Bad Online!

5.Bad Online! Hate the Friend Codes

  so i would personal pick the DS ( i have both ) because i like the nintendo games im stuck play pokemon =( but i like watching movies and stuff on my psp and like the gta games. waitin for God Of War 4  the PSP tho.

I think xstonexcold316x summed it up perfectly. One system has some great games with a touch screen while the other, while having some pretty decent games, is more or less a multi media device rather than a gaming system. It's all about what you prefer and what you want the system to do for you.

If you are more money constrained, I would definitely recommend a DS Lite (regardless of what games you play). Otherwise, if you like console/action/racing games, spend the extra money and grab a PSP.

The DS, because the PSP is missing an analogue stick.

The more I play my PSP the more I realize that certain games require a second one. There alot of games that do not need such camera control so old school rpgs, 2d fighters, card games, puzzle games and unique games are good on the PSP.

The one MAJOR negative is the UMD loading. My favorite feature is the standby mode. You can put system on standby come back days later turn it on and it is picks up right where you left off. I am not sure if I said thise here before but the only thing that makes the PSP less than perfect is the amount of ram. If it  had more it actually might solve many of the issues that system has. 

PSP it does more.