For larger sites and fewer GCPs, the Matrice 600 with the Phaseone camera is the way to go if you can afford it. Drone, gimbal and camera are around $50k. For this project site all 9 GCPs were utilized for control. The 3D survey mapping was completed by the EPS Group photogrammetry department for the final deliverable.
The Inspire 2 does really well and is capable of producing survey mapping to acceptable accuracies. SMMS Inspire 2 was used for the above flight. The cost of this drone setup was $7,500.
The Mavic 2 Pro holds its own however it needs more GCPs to improve on the accuracies for the project site above.
"Not all drones/cameras are the same nor do they produce the same results."
First determine what your deliverables need to be, then select a camera that will meet the accuracy needed for the deliverables and finally select a drone that will carry the required camera.
The costs of the drone, camera, time and GPS equipment needed to set the required number of GCPs all factor into the cost/benefit ratio for just which drone system will benefit your survey mapping operation.
As nice as the Matrice 600 with Phaseone camera is for survey mapping, it doesn't have video capabilities. The Inspire 2, Mavic 2 Pro and Zoom drones are perfect for capturing videos and oblique imagery.
Every survey operation at a minimum needs two drones. A high end one for survey mapping and one for videos.