It's not like previous Godzilla movies set the bar very high.
In all seriousness, this feels like the first film in the franchise to really push the envelope since the original. I would've said G84, but I'm honestly not that big a fan of that one despite its frequently agreed-upon merits.
The original is really the one to beat for me and I can't personally think of any other film that can hold up against it. Hope the Legendary Godzilla becomes a franchise of its own. I'd love to see where they take the character (and maybe reintroduce some classic Toho friends too!).