91 PF Warped Rotors

I am considering replacing my 4x2 91' Pathfinder's warped rotors with slotted or drilled rotors. The oem rotors warped at 15k miles. After turning the rotors and new pads they warped again at 36K miles. Does anyone have any recomendations or coments? Are slotted rotors better than drilled rotors?