Definitely panties ...most of my wife's bulls love seeing her in sexy lingerie .That moment when they feel and rub her pussy through the panties , slip their hands inside , get to slide her panties down and see her pussy for the first time .It all turns me on too especially when the guy peels them off and my wife is fully exposed to him .I know how excited she will be exhibiting herself to him and anticipating his cock inside her.Panties seem to emphasise how naughty my wife is being by letting another man enjoy her body