When Legacies first came out, I was a bit skeptical to watch it at first because to be honest, I didn't like The Originals very much. For The Originals, I only watched the first season because I felt like the whole plot of fighting over land got boring fast and was way too stretched out.
Legacies so far only has one complete season, but it's already much sadder than both The Originals and The Vampire Diaries. Also, because it's technically the second spin off, it picks right up and immediately introduces a plot, instead of holding back with the exposition like The Vampire Diaries and The Originals.
One of the best parts about this show is the little nods to it's past series. It almost gives closure to how the characters from The Vampire Diaries have been. It tells how Damon and Elena have two kids, Matt was sheriff for the first season, Bonnie still lives in Mystic Falls, and Jeremy and Alaric are still in touch. There's also a couple of scenes in Legacies where it almost duplicates The Vampire Diaries, like during the Ms.Mystic Falls Pageant where Penelope and Josie touch each other while dancing, and the judge almost repeats the same exact thing that was told to Stefan and Elena when they did the same, that this dance was strictly a non skin to skin dance.
I think Legacies may be my favorite out of all three shows