LotR score is my 2nd favorite movie score of all time, but it's still a bit of difficult to decide, because you're not asking for our favorite track, but our favorite theme. These themes your provided are mostly made by combining two or more different tracks. I guess I like Rohan's theme the most, although it depends on my mood.
Generally, I love the themes in the LOTR movies. I must admit, however, that I have difficulties telling them apart. One scene has always been very clear to me: Pippin singing for the Steward while his army rides toward certain death. It is beautiful as well as cruel.