Which is more used in present automation industries, PLC or SCADA?

PLC is a part of the SCADA system. Its optional to build SCADA system or not but its essential nowadays to use PLC for control 

if you ask as concept, the PLCs and SCADA systems are close in use because the plc is the way that scada system could collect data to be monitored or analysed.

and if you ask as career, plcs career is more and available if it compared to scada which need professionality