Welcome. The automatics have the L99, manuals have the LS3. As far as a good deal, I suggest checking KBB and/or NADA; they will give you a good idea of the price range.
The 2014's had just come out when I was in the market; after test driving and looking at both side by side, I personally liked the looks of the 2013 SS better, so that's what I went with. It really comes down to personal choice, all the Gen 5's are well built, great cars, so you really can't go wrong.
Good luck in your search
