Most of the FH soundtrack stuff gets me really nostalgic, so really I love it all. Plains3 and Plains2 are really good, one of them sounds like a cool remix of the Last of the Mohicans(?) main theme; I forgot which one sadly, but if you listened to both I'm sure you'll find a similarity.
The caves music is really sorrowful too, which I really love and again brings back memories in my old newbie days. <3 Can't really pick which one, I guess, then.