Unfortunately, there isn’t really a right way to do it. There’s just your way and you need to figure out what your way is.
My way is that I always go with the plot idea that excites me. I never get one, I get several, and if none of them are appealing then I sit and wait for the right one to appear. It can be three hours, three weeks, or even three years depending on the project, but when I have the idea that’s right for the story I want to tell, I just know.
I’ve had characters meant to be villains turn into heroes and heroes into villains. Sometimes it means I throw out my entire outline or whatever I had planned because the story is moving in a direction I didn’t anticipate. Instead of beating it back into line, I just go with it. The story knows what it wants. Ultimately, it’s always the most interesting/unique direction. My more logical side often wants to balk and go, “Oh, but you’ve already done so much work!”
Well, all that work led me here and now it’s just more work.
If it’s a choice between safe and unsafe, I usually go with unsafe.
Never think about what other people will think or how your reader might want it to end until after you’ve made your decision and written it. It isn’t about anyone else. This is you and your story. You decide what happens.
Trust yourself. Trust your gut.
Listen to it.
Ultimately, you do know best.
At this stage, cerebral thinking will trip you up. Intuition is your friend. Go with what you want, justify/figure it out later.
If you really can’t figure it out, make a list of pros and cons (an honest list) where you state your reasoning off the top of your head. Go with the one that’s what you want rather than what you think other people do.