Any really for the reference cards, if you get a super or over clocked model, think EVGA or MSI or Gigabyte are the better ones of the lot.
Depends what you are actually looking at, if its just a standard GTX460 then ASUS, POV, EVGA, GIGABYTE, MSi etc are all about the same in price/performance, some offer game bundles some offer more/less warranty. Choose which ones in is your budget range and see which has the more "offers" connected to thatr card with a decent amount of warranty linked.