X-Men movies in order

So which order should I use?

Release order. It is the only one where the contradictions make sense, because you watch the retcon happen. Days of Future Past lands as the dramatic reset it was written to be, rather than as a confusing inconsistency.

Chronological order is still interesting on a rewatch — the prequels march neatly through the 1960s, 70s, 80s and 90s — but it forces you to watch two incompatible versions of the same history back to back.

What you can skip

This is a franchise with real weak spots, and skipping is reasonable.

• X-Men Origins: Wolverine is contradicted by nearly everything after it. Safe to skip.
• The Last Stand is partly undone by Days of Future Past anyway.
• Dark Phoenix and The New Mutants are the end-of-era films, released after the Disney acquisition was underway, and neither is essential.
• The Deadpool films connect only loosely. They can be watched at any point, and require almost no X-Men knowledge.

The three worth watching regardless

X2 is the high point of the original run. First Class reboots the series with real style. Logan is the best film here by a distance — a genuinely great late-career western that works even if it is the only X-Men film you ever see.