Of course, since the question was...what do you NEED in a deer gun?. If we put the emphasis on NEED, things can change drastically !
My wife's dear, sweet aunt (and her husband) lived on their 1000 acres bordering a state park and very near an Indian reservation all her adult life (now deceased).
She used to hunt for "meat on the table" and harvested many deer and one black bear..
Her weapon of choice (all she had)...was an old H&R single shot 20 gauge w/slugs..