This form shows the usage of different choices fields.
The Classic Select uses a Django ChoiceField using the <select> widget as provided by HTML. This is the default and shall only be used for fields with a very few choices, say less than 10. It can't be styled through CSS.
The Static Opinion uses a Django ChoiceField using the new Selectize widget with a fixed set of choices. It shall be used when the number of choices exceeds 10 but also is well suited for less.
The Dynamic Opinion field shows a ModelChoiceField using the Selectize widget configured to query from the associated Django Model. While typing into this field, the number of choices narrows down to those matching the search query string.
The Few Opinions field shows a ModelMultipleChoiceField using the SelectizeMultiple widget configured to query from the associated model. It behaves similar to the Selectize widget, but allows to choose one or more options. It shall be used if the maximum number of selectable options does not exceed more than say 10.
The Many Opinions field shows a ModelMultipleChoiceField using the DualSelector widget configured to query from the associated Django Model. It shows two <select multiple> elements, the left offering all available options and the right to keep the selected options. It shall be used if the number of selected options can exceed any number.
The Annotation field is just added as a reference to compare the feedback from the Selectize widget with a standard input field.