I’d have to watch HOUSE OF WAX and MYSTERY OF THE WAX MUSEUM back to back, but I can’t seem to recall any real discernible differences in quality. Maybe I’d prefer one over the other slightly, but both have a place in my collection. As far as the reporter angle making MOTWM more interesting, maybe - but I like straight shock value too. To each their own.
HOUSE OF WAX I appreciate historically because not only was it an important step in establishing Vincent Price as a horror star, but it is one of the very few, straight up horror movies post 1946 and pre 1957 that has no sci-fi angle to it. Just a straight forward horror movie, something that era I feel needed a few more of.