Not an expert, but I've been cooking for 45 years. I'd prefer the sink across from the fridge. You'll be prepping beside the sink, so the distance to scoop, pivot, and drop is less in option #1.

I am answering your question on the other thread here. My island is about 4' x 6.5', and I really like the location of my prep sink. I do all my prep work to the right of the sink, and it is very convenient to the refrigerator and stove. Of your two options I would definitely prefer the first. The second options puts the sinks very close to each other. I will add a link to my finished kitchen thread (with dimensions somewhere in there) in case that would be helpful to you.

http://ths.gardenweb.com/discussions/2684360/its-done-and-i-love-it

Good luck with all the decisions!

You didn't ask for this advice, but have you considered switching your clean-up and prep areas? You could arrange things so that you're prepping in front of a window, closer to the cooktop. I think I'd switch the oven stack and fridge, too. It will be easier for everyone coming from the dining area, and other areas of the house, to access the fridge. Dishes can be kept in the drawers to the right of the cooktop and below ovens. Which side of the island to locate the prep sink would then be a moot point. Crude rendition:

While I'm at it, I might as well rearrange your furniture. ;)