While I agree that BG1 pales in comparison to BG2, I'd still recommend at least a playthrough...
Much of the intro to BG2 is to stir up some emotion about what is happening (during the escape), and it's impact hits harder if you know what the heck they're talking about.. hehehe
Also, some of the revelations you learn in BG2 won't have the same effect if you haven't experienced the first game. Lots of "AHA!" moments to those who ran BG1 first.
However, in any case, you can't lose no matter what order you play them in.. though if you can only choose one, I'd have to pick BG2. One of my favorite-est games ever.