It definitely depends on one's perspective! I (thankfully?) was not blessed with golden ears, so I am one of those that does not hear differences among amps. I'm not saying others do not hear differences, I'm sure some people can and do, but how much is that worth to you? I think part of the price of course of any good component should be its warranty and customer service - if you do have trouble - it should be as easy as possible to get in touch with a company and get resolution ASAP. Anthem does have good customer service. I don't know about Emotiva, no personal experience. Feature sets of course play into price as well.
And if country of origin matters to you, USA vs. Canada Vs. China or wherever, you'll pay more for the "locally grown"one for us in NA at least, but that's O.k.
I just can't justify putting out the cost of some of these amps (that DO sound great) for everything else you get!
All perspective and how good your ears are!!
I can tell you that for me, they'd all be the same. They might not be for you though. I'm not sure about Sunfire, but I know depending on where you buy, the Anthem can have a decent trial policy, and Emotiva does. So factor that into your purchase.
Also to consider - power efficiency, size, and so on, if that kind of thing matters to you!