Both. Lol. I was kind of excited to do so because of the whole version exclusive gym leader gimmick and for being the first and maybe only games that I got on launch. I also predicted they could possibly be my most nuzlocked games which so far might be the case.
Shield because of Galarian Ponyta/Rapidash. It really broke the pattern for me, as every other generation I had always defaulted to the "first" of the pair (Red, Gold, Ruby, Diamond, etc.). Galarian Ponyta/Rapidash was that important to me. Even though I also love Zacian and am sad I have never been able to get it.
I got Shield because I intially preferred Zamazenta to Zacian, although now I would happily swap Shield for Sword if I could be bothered to play through the game again. Might be a few years before that time comes, though.
Honestly don't remember why I got Sword, but that's the one I went with. Maybe because I like blue more than red? Who could say. I've been debating getting Shield as well so I can fill out some more of the Dex and battle those other leaders, but I'm having a hard time finding a justification for that extra purchase lol.
I got Sword on release then Shield for Christmas six weeks later. I've restarted them both multiple times, but Shield I have over 80 hours on my current save, which I started the run on mid-October, mostly in part to my completing the Pokedex. I'll likely restart it in due time.
I was pretty indifferent on which version to get at first, was leaning towards Shield because I prefer Zamazenta integrated shield to Zacian just holding the Sword. That was until I discovered Galarian Rapidash existed and I had to get Shield because Pride Horse. In the end I'm glad I did because I also much prefer Allister and Melony to Bea and uhhh the other guy.
Alyssa - Multiple time Pokemon Champion, Professional Cute Demigirl and Bug Type Enthusiast
Fire Red Flying Monotype Challenge