Godzilla
As a massive Kaiju fan this film has been in my watch list for way too long. This is easily one of the most harrowing yet moving films I think I've ever seen, with it's grounded compelling characters that perfectly encapsulate the post atom bomb tension and grief Japan felt as a nation, that hit me like a 50 foot tall truck.
Overall this is THE monster film. Godzilla 1954 is nothing but deserving of the impact it's left on pop culture, it's a product of its time that'll probably never be replicated again.