DS Lite is more crisp but it's boardered. I'd pick the SP irregardless though as I think the DS Lite's D-Pad is absolute trash.
If you're feeling comfortable playing as is then stick to the Lite. If you find a good opportunity for an AGS-101 and plan on playing more GBA in the future, get it.I read a lot of speculation that the GBA SP AGS-101 has more color and a better screen than the DS Lite, but I wouldn't know personally.
I'm currently playing for the first time some of the GBA Pokemon games on the DS Lite. (You are right) I wish it wasn't bordered the way it is.
I was just curious if I am currently having the best experience at the moment.
These guys are basically where it's at when it comes to GBA games. None of the other models that are GBA consoles compare to these two. Maybe if I used one physically I could notice the difference better. I feel like the AGS101 has more of a 3D effect than the Lite and possibly more color.AGS-101 definitely has a better screen. On top of that the buttons use micro switches so they're nice and clicky just like on ds phat, while the ds lite does not use micro switches so they're mushy.
It's hard to tell on camera, but I can definitely see the difference in person.
Also the image is a bit smaller on ds lite.