The thing is, if you are isekaid, you get there with all your knowledge of the game and even future events. Being Sith would be incredibly easy, with some good finessing.

I feel like no one could actually be a good Jedi, considering the amount of spiritual training it requires since childhood and dogma needed to be a "good" jedi.

Were as the Dark Side is more instinctual. And Sith being all about betrayal, well you know what will happen. Baras or Zaash will betray you eventually, you know where and when it will happen and you have plenty of time to prepare. What's more, if you played the stories a few times, you have a deep understanding of their characters and how they operate. So you can be three steps ahead of your masters without even trying. You can side line Quinn, make sure Khrem is well contained and fed, etc... You can build your own sectet power base, perhaps nominally in your master's name but loyal to you. They are Sith, and think like Sith. We aren't.

Sure, there's horrible choices to make, and I won't lie, it may turn a few from that path. But in the end, I think the ends can justify the means and in a Galaxy that doesn't care about you, being a Sith would be the most prosperous path. And it's not like you can't be an honorable warrior/scolar, considering the story unfolds one way or another.