These are the hard-copy editions I use for my Tolkien posts. I use them because they are the ones I happen to own; I am as specific as possible here because the pagination does not match up from one edition to the next.
I consider only The Hobbit, LOTR, The Silmarillon, and a few other things like some of the poems published in The Tolkien Reader to be canon. I may look at The Book of Lost Tales, Unfinished Tales, and The History of the Lord of the Rings at some point, but for now I consider all that stuff draft material, and Tolkien drafts are sort of a rabbit-hole.
The Silmarillion, Illustrated by Ted Naismith. 1998. Houghton-Mifflin. (Original text copyright Allen & Unwin, 1977.)
The Hobbit. 1973. Ballantine edition.
The Lord of the Rings. 1994 hardcover boxed edition. Text conforms to standard Houghton Mifflin edition, 1998. Cited in-text as: “Fellowship of the Ring,” “Two Towers,” and “Return of the King.”
Foster, Robert. The Complete Guide to Middle Earth. I am unsure about the year because my copy of this book has no covers. I have literally read it to shreds. Published by Del Rey, I think c. 1987.