In this paper, we evaluated and compared the integral quality of different omnidirectional contents for two head mounted displays (HMDs), namely HTC Vive and Oculus Rift. We also investigated motion sickness and head-movements. To this aim, we categorized omnidirectional contents into three categories based on the degree of motion: high, medium and low motion. For assessing simulator sickness, we used the Simulator Sickness Questionnaire for each of the contents in both HMDs. The viewing direction for subjects while watching the contents were recorded in terms of the three coordinates yaw, roll and pitch. Experimental results show that HTC Vive offers better integral quality compared to Oculus Rift. We also compared simulator sickness scores along with the behavioral data for different contents and HMDs and discussed the results in the paper.