As far as I know, the only books published while Tolkien was alive and the only books that have his blessings. The rest should be taken with a grain of salt imo. Remember you are dealing with a master revisionist. The rest were pre-works or musings.The Hobbit
Farmer Giles of Ham
*The Lord of the Rings
*The Adventures of Tom Bombadil
Tree and Leaf (On Fairy-Stories plus Leaf by Niggle)
Smith of Wootton Major
*The Road Goes Ever On
Not counting of course critiques and scholarly works.
I love Unfinished Tales as much as any Tolkien work, but it was never meant for publication. And certainly the Sil was never in a finished form, and I would hate to be the one who broke the news to him of his letters being published. Certainly they weren't the only letters he had written and who knows how many non-published letters had contrary views.
I know there are a lot of "Tolkien" books out there and they provide many hours of good reading. For me though there are the Hobbit, the LOTR and the Tolken Reader as far as ME goes. The rest should have a large asterisk next to them. Again not counting critiques or scholarly discussion.