Tough to get a good choice this time of year, especially after a few snows.
Borat mentioned a good Simplicity and I don't think anyone will disagree. But you may have trouble finding one, so check Sears and John Deere. They both have the same machine (some Sears sell the Snapper brand, it's not one of the Craftsmans) with a different name.
Take a look at the specs and pictures of the following:
http://www.simplicitymfg.com/products/snowthrowers/large_frame/
http://www.simplicitymfg.com/products/snowthrowers/large_frame_dual-stage/specs/
http://www.snapper.com/products/snowthrowers/large_frame_dual-stage/
http://www.snapper.com/products/snowthrowers/large_frame_dual-stage/specs/
http://www.deere.com/en_US/ProductCatalog/HO/servlet/com.deere.u90785.cce.productcatalog.view.servlets.ProdCatProduct?pNbr=LP1695441&tM=HO
http://www.deere.com/en_US/ProductCatalog/HO/servlet/com.deere.u90785.cce.productcatalog.view.servlets.ProdCatProduct?pNbr=LP1695442&tM=HO
It could all boil down to what's available
now, your confidence in the dealer, and who has the best price. Oh, and your favorite color ;)
Who the hell let all the morning people run things?