Defintely Fulltone OCD. I am personally using one and its one of the best low-med overdrives and booster i have used. I have tried all 3 xotic pedals. They are very good at what they do. How the ocd differs is that it has more gain, tighter bottem end and more pronounced highs. There is a switch on the OCD to change between a high gain and low gain mode. One which is more transparent and one which is more compressed.
The new versions of the OCD have much lesser mids in them. If ur using it as a boost...i hope ur using it with a pedal that has some mids in it.