I've immigrated to the United States, and my wife is American. We are very close to sending our application off to have her immigrate to Canada.
I immigrated here quite a few years ago on the K-1 visa (the same one from 90 day fiance.) As far as immigrating is concerned, the K-1 is pretty nice, because it allows you to basically wait out the processing period in the United States while they scrutinize you for a green card. That being said, my understanding is that processing times under the new administration are *way* longer, but I don't know that much about it.
If nothing has changed, I would probably go the K-1 route if you were to bring her to the United States. I wouldn't get married first, because I believe that exposes you to a significantly longer wait (because you don't have the option of applying through the fiance visa.) That being said, a K-1 visa requires that you get married in the States.
Based on what I'm seeing, the effort to get to Canada is front-loaded. You seem to have to do it all at once, and there is less follow-up later on. If you go the K-1 route, you basically have to submit three different applications - the first to get the fiance visa, the second to "adjust your status" and get a conditional green card, and then the last to have the conditions lifted from your green card so that it's good for 10 years at a time. All of that happens over the span of 2 or 3 years.
Moving to the U.S.A. was a big adjustment for me. I found a good career and everything, but there is a lot to get used to (health care and so on.)
Alberta is probably the closest province that you can get to the U.S.A., so that works in your favor I suppose.
Make the decision very carefully. This is a process that you only want to do once (speaking as someone who has gone through it once and is going through it again.)