which sensor better to use for slam?

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LIDAR sensors are so far the most reliable (if expensive) sensor for performing SLAM with mobile robots. Camera-based/Visual SLAM works well in some scenarios but tends to be (much) more brittle generally. You can use a 3D SLAM approach like ethzasl_icp_mapper with a rotating LIDAR or you can combine a (internal) 2D approach like hector_mapping with a rgb-d sensor and IMU data to perform 3D mapping. That's what we do in this video and as can be seen, the robot operates autonomously in the Rescue Arena for 20 minutes without running into obstacles like half height roll/pitch ramps.