They're both more than satisfactory, but the back-lit model is brighter, and widely preferred. I have a front-lit SP, and the screen is still bright enough for me to play it in any location that I've attempted to play in, thus far. So either choice is acceptable.
Front-lit Model No. = AGS-001
Back-lit Model No. = AGS-101
But I agree, the DS always felt so clunky when playing GBA games on it, plus the backwards compatibility is lacking in comparison to the SP.
Also, yeah.... $60 is a little much. I scored mine for $25! I would check a few local game shops first.
PS: Fuck you, guy!