You did good yecul, it's a shame most people don't like to read manga AND comics (and European comics by the way). Most people just focus on one of these and loose a lot of great stories and art from the other two genres.
From your haul I recommend:
Rurouni Kenshin: You got the complete series and one of the best ever. As others have said don't worry about the quantity of volumes, you'll easily read 5 a day!
Zombie Powder: Most people seem to like it, I thought it was ok, but you might want to try it at least one volume.
Case Closed: I'd by the first 7 volumes for you if I didn't live in the end of the world, that series is around since 1994, it's one of those cult classics you either hate or love, I happen to love it.
You've got Naruto, Bleach, Soul Eater and D. Gray-Man, those will be easy to sell I guess since everyone who's into manga reads them... Their quality is debatable, but you might want to try and read at least one volume.
Happy readings, and if you do feel like getting some more and need advice feel free to PM me, I read a lot of manga!