The only Godzilla film that is truly shit is Godzilla's Revenge and that's cause its a best of clip show with some wacky kid antics slapped. I'll split up recommends into 3 categories
Totally Serious: Return of Godzilla, GMK, Shin Godzilla
Middle of the road: Godzilla vs Biollante, Godzilla Against Mechagodzilla, Mothra vs Godzilla
Absolutely Goofy: Invasion of Astro Monster, Godzilla vs Megalon, Godzilla vs King Ghidorah