For me, it is the old BuckeyeCam Orion. The primary reason I like it is reliability and lifespan. I used many brands and cameras prior to investing in a BuckeyeCam system. In fact, I even taught a class on trail cams to our state hunter education instructors. We ask a lot from trail cameras. Point and Shoot as well as cell phone cameras take great pictures for low cost, but they have an operator. In most cases, the operator either focuses or initiates an autofocus that allows the camera to make adjustments before snapping a picture. We don't expect them to detect game with a low false alarm rate, trigger in less than a second to capture running/flying game, take good pictures without alarming game, and do so for weeks or months at a time operating unattended in all weather conditions.
I bought my first BEC when they released the Apollo which was a stand alone precursor to the Orion with an upgrade path. I soon upgraded it to the wireless Orion. Over the next year or two I fleshed out my 11 camera Orion network. Most of these cameras are closing in on 10 years of 24/7/365 use with no failures I can blame on the camera. I have recently sent some of them back for refurbishment. This includes wear items like the lexan lens cover, connector replacement which wear over time and such. With the proper balance of programming and solar panels, they run completely unattended for many months or even years with no attention. They transmit full resolution images to my PC at camp with no recurring cost unlike cell network based cameras.
These cameras are not for everyone. Reliability and longevity is most important in applications where you don't want gaps in data caused by missed/slow triggers, dead batteries, and camera failures. Research projects and collecting longitudinal data for making QDM decisions are good examples of applications where reliability in important. These cameras have a high up-front cost, and setting up long distance RF communications at these frequencies in challenging environments requires some technical aptitude. However, when you amortize the cost across the lifespan (almost 10 years and they are still running strong), the cost dramatically drops. If you consider your time checking cameras and maintaining them as valuable, the savings is even more over the long run.
While they may not be a fit for the casual hunter, the advantage of limiting human influence when checking traditional cameras can be very beneficial to most applications.
They are certainly my personal favorite because my primary purpose is supporting QDM decisions but that doesn't mean they are a good fit for others.
Thanks,
Jack