What would Tolkien like most?

[The Sixth Wizard]

I'd say the Shire would be the one of the only ones Tolkien could really relate to, because he was from a period of time that didn't include digital effects or all the other things we have in movies these days.

I must say he would have loved King Theoden's speech in RotK, and the whole grandness of the Rohirrim.

I think he wouldn't have minded the idea of Elves at Helm's Deep much, at least until they started fighting so freakishly...

[Morthoron]

Here is Tolkien's caveat regarding M.G. Zimmerman's proposed 1958 screenplay:

I would ask them to make an effort of imagination sufficient to understand the irritation (and on occasion the resentment) of an author, who finds, increasingly as he proceeds, his work treated as it would seem carelessly in general, in places recklessly, and with no evident signs of any appreciation of what it is all about.

And then criticizing each scene in earnest:

...yet one more scene of screams and rather meaningless slashings.

I believe Tolkien would be too appalled at the many blatant variances from his original story to watch more than a portion of FotR before finding suitable Orkish curses to exorciate the production while leaving the screening, never to watch the remaining 2 films (which would be just as well, as The Two Towers would have thrown him into a fit of apoplexy).