The selection of algorithms is based on the nature of the study. We will help you in a better way if you kindly share some details about your research. Meanwhile, I will suggest YOLOv2 and YOLOv3 for your learning.
It depends on how you want to apply the algorithm; for example, the YOLO family is perfect for object detection and tracking, but it is not very supportive of low frame rates. For the initial stages, you can start with YOLO or other SSDs