It depends on what pokemon are available in which version and which one my friend picks. We've always had this sort of rivalry between us since we were kids, I'd always pick a starter and coincidentally he'd get the one stronger to it; I'd pick... say, Diamond, he'd get Pearl, etc.
For now, I think I'll play AS first because I lose my original Sapphire cartridge when my step sister stole it and sold it for money for her purse (DIDN'T EVEN GET TO FINISH IT THAT LITTLE). But yeah, also because I feel like I'd be in more danger from drowning than I would from getting a sunburn. Also because I played Y last time, and I kind of want to bounce back and forth between the "warmer" and "colder" colors (Black and Black 2 being the exceptions). I just hope that the stories will be different enough so that it won't be too much like the originals either way.