Firstly, let's talk about where this cooler will fit. Everywhere; well, almost! - Seriously, I have assembled a few SFF and HTPC chassis' that these coolers would be very handy in. There are solutions already on the market that will offer cooling solutions in tight confines, but some don't come with a fan, and most come with a much tougher retail price tag to have to swallow when you buy your cooling solution. The performance of both coolers is very good considering the compact nature of the fin arrangement and the fact that it uses a 92mm fan that can run essentially silent if needed and wont tear into your eardrums at full go.
As far as the choice between the two coolers, my advice is first to go with performance which leaves the ZT-570D the one to buy. So let's move to aesthetics; I prefer the copper fins, so the ZT-570D is still ahead. Since both kits offer the same fan, hardware, and packaging, there isn't a clear winner here. The game always starts as best two out of three, and this game was won by the more impressively performing ZT-570D.
Typically when we see two coolers made like this, the all copper equivalent cooler can get quite expensive over the aluminum counterpart. Now I realize there is less material in this style cooler than a tower style cooler, and ZEROtherm passes the savings onto the customers. For a little less performance, you can acquire the ZT-560D for $24.99 at Newegg.com. For better performance than stock and a price like this, there is no way to lose. If you prefer the better performance and the all copper look, the ZT-570D can be had for $32.99 at Newegg.com. That's right, it's only eight dollars more!