Prequels tend to generally get a lot of dislike/hate as a category, with a lot of the usual tried-and-tested arguments - "There's no suspense because we know what happens", "Revealing the character's backstory destroys the mystery", "Continuity errors!" etc. And very often, those are true. And yet, studios wouldn't be making them if they were all inevitable failures. Ergo, there have been some good prequels, even great ones.
In that vein, what are some prequel films that you've personally liked and/or regarded as being good?
If you like you can choose to interpret 'prequel' in the loosest sense, since a lot of reboots functionally serve as 'prequels' of sorts, in terms of turning the clock back to an earlier era than the previous iteration of a series or franchise.
I think X-men First Class was definitely a solid prequel. McAvoy and Fassbender were perfect casting as young Charles Xavier and Eric Lensherr, and Matthew Vaughn did a brilliant job crafting a compelling story without too many iconic or even recognizable X-men characters (Notably this is the first X-men film without Wolverine in a significant role!). I loved how the film balanced the tonality and aesthetics of the Silver Age comics with that of the original film trilogy. Mystique was fleshed out into an actual character in First Class, which pretty much launched Jennifer Lawrence's career, and even Hank was given the focus and development that he lacked in X3. All in all, a near-perfect origin story for the X-men.
JJ Abram's Star Trek is another one - though arguably its not technically a 'prequel' so much as it is an 'alternate universe' story and 'reboot'. Still, broadly speaking, it could be viewed as a prequel of sorts, and I think it does a phenomenal job with James Kirk's origin story, the beginnings of his lifelong friendship with Spock, and the Enterprise crew coming together. The time-travel/alternate universe aspect makes this the rare 'prequel' where you get to see the original/future version of an iconic character come face to face with his younger self - getting Leonard Nimoy back as Spock was truly a stroke of genius!
From one 'star' franchise to another, Rogue One is another favorite prequel of mine - one that doesn't focus on the same characters, but rather on the setting. It reminds us that there was always more to the war than the Skywalker clan's drama, and that war is hell in a way that the cute lasers of the original trilogy didn't always convey.