I voted for both. Being a big console fan, most likely I will buy both of them when they are released here in Europe. Then, only time will tell which is the one I finish playing and buying games for.
The PSP looks more appealing to me as of now. I just hope its screen is resistant and the machine durable. Most likely you'll be able to buy some cover-lid that totally protects the face of it while you are not playing. In any case, I don't really use portables to play on the go, rather to use them when I have to stay out of my place for a long while, when I'm abroad or on holidays, so I just play them lying in bed.
For example last year I spent 2 months in Newcastle in a student residence, so I had no TV and no computer in my room. I brought my GBA SP and played the shit out of my 5 games during that time. However now I have a Treamcast ("portable" Dreamcast with LCD screen, but it sucks), a PSOne+LCD combo and a laptop (not a powerful one). Still, other than the laptop, I'd rather bring the PSP with me.
I prefer one big screen like the PSP one to 2 small screens of the DS. I couldn't care less about one of them being tactil. On the same time I don't see the point in the PSP being able to display movies if you have to buy them in its specific format.
I'm also a bit pissed with Nintendo because of hand-helds. I bought a GBA 2 years ago, and barely used it because of the shitty screen. Then 1 year ago I had to pay again full price for the SP, and I love it. And now, will I have to buy yet again another system, the DS, that plays the same games? OK, it also has new games, but still they are releasing it too soon. I guess the PSP launch forced them to do so... They start to remind me of Sega and their TV consoles: they were abandoned/replaced with new ones too early (I'm talking about Mega CD, 32X, Saturn, Dreamcast...).
About anounced games, the PSP ones look amazing to me, specially in such a screen. Just the Metal Gear one justifies the purchase of the console alone.