I have a few Warn 3/4" D rings (came with my winch), but brand doesn't matter that much. Just run down to Home Depot, or an industrial / farm equipment store, and save yourself the shipping costs.

Here are a few examples to give you an idea of what to look for:
http://www.quadratec.com/products/product_search.php?kw=d+ring&submit=Go%21