I'm trying to work the muscles behind and beneath the armpit (teres minor, teres major, upper part of the latissimus dorsi)
Are overhand pulldowns and pull ups better or are underhand pulldowns and chin ups better for this area? Elbows tend to flare out more in overhand
I know there's not that much of a difference, but I'm curious
Whichever you feel more comfortable doing.
I mean personally I would go with overhan but keep grip shoulder width. I find with underhand grip its easier to fall "under" the bar and lean back, which moves more focus into the mid back.
Don't completely neglect the one you choose not to do though.