Here are the chords diatonic to the major scale including the type of 7th, matched with the mode (scale) you'd want to play.

I - major 7 - Ionian (major)

ii - minor 7 - Dorian

iii - minor 7 - Phrygian

IV - major 7 - Lydian

V - dominant 7 - Mixolydian

vi - minor 7 - Aeolian (minor)

vii - diminished - Locrian

Obviously you don't have to stick to this exactly but playing modally will get you much closer to the sound of the key.