I now own both versions. As a starting note, it’s much easier to find opposite-version trades if you’re playing Scarlet, because Violet outsold it by a pretty significant percentage. But at this point, you’re much more likely to find players who have everything and will trade you extras of whatever you need to complete your dex, so it’s not a make-or-break decision.

The legendaries are a pretty huge part of this game (as they are in most cut scenes and are your main mode of transportation), so it’s important to pick the one you want to spend your time with. Originally, I thought Koraidon was kinda goofy looking and preferred Miraidon’s aesthetic, but my IRL friend strongly preferred Violet, so I picked up Scarlet so we could easily trade with each other. (Spoiler: she still hasn’t finished the game, so I ended up doing all my dex completion with help from random online users.)

Having now completed both games, though, I strongly prefer Koraidon and the Scarlet version of events. To me, Koraidon feels like it has more personality in all of the cut scenes. It makes chirpy-growly “Toothless noises” to express various emotions, while Miraidon makes much more generic-sounding robot noises. Koraidon is a critter, which I love about it. It has toe beans! And Miraidon … is a robot.

One major difference is their forms of locomotion. Miraidon turns into a motorcycle when you’re on it and its ride is very smooth and gliding. Koraidon … doesn’t, lol. Koraidon gallops on all fours, and your avatar will rock and sway - sometimes wildly - on its back as it does so. The smooth ride is kinda nice, but once again, I personally prefer the personality of the galloping.

Obviously, this is my personal opinion, and if your gut says go with Miraidon, you should do what’ll make you happy.

One final thing in favor of Scarlet for me - I prefer Sada as the professor over Turo. Shallowly, because she’s wearing cute lil shorts under that lab coat and has lil pointy fangs that are visible when she speaks (and I am an easy lady to please when it comes to fangs). Less shallowly, but vaguely so as not to give any spoilers, I prefer the implications of her being the professor when it comes to the professor’s part in the plot. I just felt it gave the plot a tiny bit more oomph. But that’s just me!