Yeah OP I think it comes down to these things:
Top priority: being together faster and not having to separate: K-1 by a MILE
The ability to go to your home country if one of your family members is sick or something: Spousal. (although you can get advance parole after K-1 and I don't know how long that's taking these days so it wouldn't rule out the K-1 completely)
And as for where you want to get married. I would say unless it's extremely important to you focus on these two points to make your decision. Unless certain people from you country are unable to be in the US that you really want to be there.
If you are going for the spousal visa budget money for visiting each other. The wait is brutal right now and not getting any shorter.