>>116943419The original (not the censored American version) is a legit classic movie, stands alongside giants like Citizen Kane or 7 Samurai as far as I'm concerned. Note that it isn't a very fun movie, though. But it is the 'best.'
Godzilla Against Mechagodzilla is a solid fun watch that actually has a small handful of oh shit moments. The closest I'd say there is to a definitive movie for the series as a whole, while still being good. Watch subbed, the cheesy dubs are fun on bad movies but ruin good ones. Was probably my favorite until...
Shin Godzilla. Just a really solid watch. Feels classic, but original too.
GMK Giant Monsters All Out Attack is good. Weird for Gidrah to be a good guy but maybe the best movie at making Godzilla feel unstoppable.
Tokyo SOS is the only movie here you should watch 'in order' (after Against Mechagodzilla, it's a direct sequel). Not as good, but good.
Those are the ones that I consider legit good and would recommend to anyone, in the order I'd consider best to fifth best. If you want hokey fun then Ghidorah the Three-Headed Monster and Godzilla Final Wars are fun in their own way.
Godzilla VS Mothra '92 is kinda funny for how shamelessly they rip off Indiana Jones and near the end Godzilla makes the coolest entrance to a battle I've ever seen in a kaiju film, maybe even any movie. But it's not a good movie overall, probably better to have it on in the background or something.
Some of the other movies have a few cool ideas or something to offer, but I wouldn't really recommend most of them.