German has four

being curious about Finnish and looking into it and determining that that is waaaayyy more cases than I'm prepared to learn.

English pronouns still have three, but yeah, the vast majority of nouns have simplified to two. Latin has six, and I have encountered some consideration of locative as a seventh, but I think the consensus is six. But I remember

Uralic languages are much more complex though. Both Estonian and Finnish nouns and adjectives decline in 14 cases

as opposed to German's three and Rnglish's two.

Polish grammar is more complex than Latin grammar. Suffice to say - we have 7 grammatical cases

I think that's still fairly strong with Slavic languages, although I'm sure we have a sufficient supply of native speakers here to correct me on that.