I know "He Stopped Loving Her Today" is supposed to be the greatest song. While I DO like it, I don't think it's even the best song George Jones did on the subject matter (that would go to "When the Grass Grows Over Me").
My favorite George Jones songs:
"The Window Up Above" - he had to BECOME a legend, and this incredible caught-you-cheating song shows HOW he became one.
"Who's Gonna Fill Their Shoes" - paying homage to the greats of country music and asking a rhetorical question, because we all know that NO ONE will fill their shoes.
"What Am I Worth" -- I think this was either his second or third single, back in the Starday era, and its bouncy, fiddle-driven melody is what you think of when you think of "classic country." A perfect vehicle for George.
"A Good Year for the Roses" - an exceptional lyrical picture ("I can hardly bear the sight of lipstick on the cigarette there in the ashtray / Lying cold the way you left them, but at least your lips caressed them while you packed") of lost love. When rockers like Elvis Costello consider this good enough to cover, you know it's a song that packs a punch.
"The Waltz of the Angels" (duet with Margie Singleton) - one of my favorite songs ever, thanks to the original by Wynn Stewart. George and Margie covered it in 1961 and did a great song proud.