Do you include Half-Life 2 in your list? (Since you've listed Half Life) I think all the stuff in there about Alyx, Dog, Barney, and Eli Vance are quite interesting. Meaning that the plot is far more character driven than the first game and successfully so since Half Life 2 and its episodes has some of the best facial animations and voice acting to date.

I include the entire Half- Life series on the basis of the core story. I do think, however, that the supporting characters in Half-Life 2 were well done. But I still think that the overall story that those characters are attached to is not very compelling. 

How could you?  I'm a complete Half-Life fanboy.  I'm with you on Metal Gear though.  I think you need to be willing to join the church of Kojima for that to work the way it's intended.