Default DPS every time. The DPS would have to be incredibly bad or a tank/healer would have to blow my mind for it to change. My reasoning for this is because as a DPS player, far too often you will see tanks and healers get most of the commendations for getting out of bed in the morning, it's not even required to actually play well. So my contribution is always reserved for the DPS players that go unrecognised for actually playing well.