2 of 2 Changed Function to Filter

PowerShell Core, 134128 bytes

Filter F{$p=($_-creplace"[^A-Z]",'').Length/($_-replace"[^a-z]",'').Length;$l=1-$p;(.({"$p upp"},{"$l low"})[$p-lt$l])+"ercase"}

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Thanks, Veskah, for saving six bytes by converting the function to a filter!