Ok Guys & Gals, I have my theory on this, I wont share it with you just yet as I wouldn't want to influence your voting If you could choose 1 outweighing factor to optimise a page for Google Base, what would it be? I am hoping for a good debate on this one.
None of the above - get as granular as possible with categorization, get a load of reviews, be the cheapest. Google Base / Shopping / Froogle / whatever they call it this month doesn't use the same algorithm as google search - the only couple of the above that matters for it are title (of the Google base listing) and attributes. Very very little that happens on the site affect it.
google base works in much the same way as other shopping comparison sites (eg kelkoo).good images will improve your chances on google base.and properly optimised titles and descriptions of your products.
I totally agree with you on the attributes and reviews. Can't see how price will get you to the top for relevance though?