HDDs aren't one of those things that are very dependant on the manufacturer, but i recommend going with one that is at least 7200rpm and 1TB, as 1TB costs only about 30% more than 500GB ones. it all depends on your needs, but don't go with 5400rpm ones, because they are slower and slow HDD can be quite annoying. from more detailed specifications, ones with bigger cache and SATA3 should be preferred, although the difference is probably insignificant.
also, make sure to pick the right size, which is 3.5'' for desktops.