If I had the $, I'd do the organic--NOT grain finished. I've read grass *finishing* does make a big difference in quality...
Check this: http://www.ozarknaturalfoods.com/common/news/store_news.asp?task=store_news&sid_store_news=12&s toreID=4352A164B6274DFC8F4930A85CEF1307
Levels of Omega-3, a fatty acid which is essential to for human growth and development, have been shown to be much higher in grass-finished meat than in grain-finished meat. One 3.5-ounce serving of grass-finished beef offers 15 milligrams more of Omega-3s than other kinds of beef. Omega-3 originates in the green leaves of growing plants, so it makes sense that grass-finished beef would be higher in this fatty acid. As with CLA, the Omega-3 levels drop dramatically when animals are conventionally grain-finished. Grass-finished dairy products are also much higher in Omega-3s.</blockquote>