I am looking for antonyms for extempore in the context of "to speak extempore", i.e. speak without notes.
I am looking for something better than prepared.
You could use rehearsed or scripted as antonyms for extempore.
Noting that OP doesn't want the "exhaustively prepared" connotations of words like rehearsed or scripted, I would suggest considered, measured, or careful as ways of describing utterances which aren't carefully pre-planned, yet which suggest a level of forethought missing in extempore.
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