So by the looks of it your looking at semi-auto snipers???
My opinion go with the CYMA M14 i've heard good things about it. I wouldent really trust AGM as much as CYMA. CYMA has really steped up there game over the past year or so (I think) but they have started making guns worth buying.
A&K Dragnov looks very sketchy and yet agian with A&K you never really know what your going to get sometimes they make good high quality guns.... Then other times you get the lemons that don't work when you want them to.
E1 G3 I was actually going to get this gun myself but went with the M16A4 instead. The G3 is very accuarate because of the barrel length but it makes it very cumbersome and hard to menouver in some situations. Its E1 so most likely your going to get a quality product.
So to make things simple its either going to be the
Echo 1 G3 or the CYMA M14.... Your pick!
http://www.airsoftgi.com/product_info.php?cPath=139_24_206&products_id=3731