All of the feeds will increase awareness (and sales) for your sites. You have to work out which is the best for your particular site and product type. For example, from our experience, we have found that affiliate companies are good for selling niche or high value products. Also, from our experience, price comparison websites can be cost effective for low value products or products that you can sell for low profit margins.
The free feeds can have a side effect of improving search results.
The available feeds can be split into 3 categories:
Advertise your website
Google XML sitemap (free), RSS feed, Google Product Search
Also sell your items elsewhere (in other shops)
Ebay, Amazon (Final price % cost and/or monthly fee).
Use affiliates to advertise (or sell) your products
Kelkoo, Affiliate Window, Shopzilla, PriceRunner, Paid On Results and Webgains. Monthly fee and/or final sale price commission.
If you look at the online information this gives a summary of each, how to join them and what they are most useful for:
https://www.mole-end.biz/acatalog/ME_FroogleMashDef.html
NOTE: We do not endorse any particular feed type and have no affiliation with any of the companies that the feeds are produced for.