All the shields mentioned by quaddy are pretty good. I tend to use either Silver Knight Shield or Grass Crest Shield if I'm parrying. Different strokes for different folks and all that.|
If I'm blocking up I use Greatshield of Artorias. That thing is a wall. No point upgrading it because the stability doesn't change and it's expensive. I do love the dull clang of metal on the shield when people try in vain to get to me through it.
XBox Live, Origin, PSN and Games for Windows Live Gamertag: teamHAM