Raise. This is not a good time to slowplay your middle set. This is a raised pot with a lot of players, and you have two cards in the playing zone (a king and a ten). You don't want to give a cheap card to a bunch of gutshot draws or to someone with a queen-jack. Focus on protecting your hand and not trying to finagle an extra bet later on. Maybe the original bettor will reraise to try and confront the field with a double bet. If so, this is great for you, whether the field plays or folds.