Best for mostScribner (authorized) · 1925
Gatsby is short and its text is stable, so for most readers the question is just which copy to own — and the Scribner edition is the canonical one, with Francis Cugat's famous 'Celestial Eyes' cover and the authorized text. Now that the novel is public domain you'll see many cheap printings; this is the one I'd still reach for. This is where I'd start.
The early versionTrimalchio (early version) · 2000
Before Gatsby there was Trimalchio — Fitzgerald's earlier, substantially different draft, which he rewrote in the galleys. Cambridge prints it whole. Fascinating if you love the novel and want to watch it become itself; not the version to read first.
F. Scott FitzgeraldThe Great Gatsbytr. Free (public domain)
FreeFree (public domain) · 1925
Gatsby entered the public domain in 2021, so the full 1925 text is free — Gutenberg, Standard Ebooks, and many cheap reprints. Free; just note the quality of random print-on-demand editions varies, where Scribner's is dependable.