I would choose the Antec VP550P ($65)http://www.pccasegear.com/index.php?main_page=product_info&cPath=15_535&products_id=18877
Because it is indy regulated, whereas the Neo Eco and Silverstone are group regulated. I don't know about the CX500 (v3 / 80 Plus Bronze), although I would expect it to be group regulated as well.
Also, in the review units at least, it used Japanese caps, whereas the others mentioned so far use Taiwanese or Chinese caps, as well as sometimes Japanese ones.
The 450W version is also good.