I'm not a fan of the package design on most of the different versions of GH/PC/PH, but there's been a few exceptions. The new PS3 Greatest Hits cases actually look pretty nice and I like how they minimized the "GH" bar across the top of the cover art. For some games, Ninja Gaiden Sigma in particular, the GH package actually looks better than the original releases.
The Platinum Hits and Best of Platinum Hits cover designs are fucking atrocious, bested only by substandard garbage like Konami's rerelease of Dawn of Sorrow. What the fuck was up with that one?
Player's Choice releases are pretty "meh", but I love it when they rerelease them later as "Best Seller" with that big ol' emblem on the lower left. I don't know why...maybe it's because it looks better when on a shelf or maybe because it kind of reminds me of the Million Seller label that I liked from the N64, but I don't find it all that bad (despite being obviously tacked on).
All the same, I'll pick up a rerelease over an original release more often than not. Sometimes it simply has a bunch of bugfixes and tweaks (like Jak X) and sometimes it has a bunch of exclusive, new content (like Silent Hill 2, Midnight Club 3, Virtua Fighter 4, etc). As long as it adds new stuff to the mix then I'm not too torn up about the ugly case design.
What are you looking for?