All parallel universes, as hinted by Genisys, as well as massive continuity discrepancies and casting changes.

I loved all Terminator movies, I'm a huge fan. This is my ranking order anyway:

1- Terminator 3: Rise of the Machines (2003)
2- Terminator Genisys (2015)
3- Terminator: The Sarah Connor Chronicles (2008-2009)
4- Terminator: Dark Fate (2019)
5- Terminator Salvation (2009)

Genisys had brilliant ideas, as well as an interesting story, I didn't like the casting at all. Especially Kyle Reese.

Rise was a great movie. Epic and exciting. The TX was a memorable villain IMHO.

The TV series was incredible. I loved it. Narrative twists, character-arcs and great special effects. Terrific work.

Dark Fate is a great movie, so underrated. It was VERY derivative, but charming nonetheless.

I loved Salvation, but it resembled a Transformers movie. Marcus Wright is a wonderful addition to the Terminator mythos.