It's interesting to me that Metal Gear has so many cut-scenes and is very plot heavy, yet I found the plot in the Souls games to be much deeper and more engrossing...yet that doesn't really tell you any of it. You have to actually find it, read items, look at the environments and use your creativity a bit. It's set up so well.
I still enjoyed the plot of Metal Gear though, although I thought the earlier timeline parts were much more interesting. All this cyber soldier stuff with Raiden couldn't be more dull to me.
I love twists on actual historical events though so MGS3 was the most interesting for me.
Hopefully that means I enjoy TPP quite a bit.