There are several methods for mounting cabinets to a wall surface. Tapcons are a good choice, if the wall is made of suitable strength material. I've had tapcons strip out due to poor quality concrete where the threads simply crumbled. I'm not familiar with "concrete block" walls, unless you are referring to what we on the west coast call cinder block. These are hollow units that are grouted in place like large hollow bricks and are made from a very porous material that can crumble easily. I often have used molly screw fasteners with great success, and I like the neat and tidy installation method. Toggle bolts are also good, if you have no plans of ever removing the cabinets and re-installing them later, but if you are hanging the cabinets by yourself, mollys are the ticket. It all comes down to what method you prefer for the load you will be supporting. Out here we definitely do not want the cabinets shaking off the wall.