"Power ballad" to my mind means pure, unadulterated cheese, so the choices that come to mind are pretty sappy. I legitimately, completely unironically love this ridiculous song:
Random aren't even a good band. They're totally unremarkable, grade D (D is for "Dad") metal slop. I mean, they were on Metal Enterprises, FFS. But, for some reason, I really like this goofy song.
I also genuinely enjoy Black Sabbath's "Spinal Tap album", Born Again. Especially the closing ballad, "Keep It Warm":
If nothing else, Iommi's familiar (and awesome) 80's skronky, octave fuzz guitar tone is all over the solo, so there's something for the alienated Sabbath fans to find comfort in.
And, if it counts for metal, I'd like to add this syrupy Rainbow fluff piece (seems a lot of people hate this song, but I think it's fantastic. I've lovedit since the 7th grade):