I have used both for typing as well as gaming, and they're both pretty good for gaming, but if you have MX Greens everywhere, you probably ram on the keys a fair bit. Alps would be more accomodating to that; Monterey switches are rather light and delicate (to the point where they actually turned me into a very light typist for a few weeks xD), whether Alps are a bit chunkier. Again though, with both, and especially the Alps board, be sure to check that the board (and therefore the switches) are in OK condition.
I have a video review on my Monterey Blue as well as my SKCM Blue keyboard, if you're interested.