I like a good scenic view, but I also like it to be a location that's meaningful to that particular couple. (First date, first vacation away together, etc.) It sounds like your top two choices check off both of those boxes. Or if there's anywhere special they liked to go in university (other than hanging out in the dorms!), that might be a nice sentimental choice, too, though perhaps not quite as picturesque.
If you plan on taking pictures and having them reminisce about them later, I think it's also nice to use a location that will give a positive or romantic moodlet. I know the waterfalls in Selvadorada will do that, but I still haven't made it to the top of Mt. K., so I'm not sure about that.