TLR cameras
For hardened film users the twin lens camera is a design that has served decades of photographers well. What could be simpler than the idea of putting one camera on top of another; one to do the picture taking and the other to do the focusing? For years the Rolleiflex range of cameras were the market leaders but there have been many good copies made. While there have been TLR cameras in other sizes, the Baby Rolleiflex (127size film) and the rare 35mm Zeiss Ikon Contaflex TLR are a couple, most used 120 sized film.
There have been designs with interchangeable lenses, Mamiya TLR, and those that have fixed wide angle or telephoto lenses like those from the Rolleiflex range or the French Tele Semflex.. The thing that sets all of them apart from other types of cameras, except rangefinder models is the un-interrupted view of the image you have as you take the picture make them great for photographing anything that may move unexpectedly as you try to take the shot, like children or animals. A between the lens shutter is also especially useful when using flash. The TLR camera has been used by all types of photographers for a wide variety of work. This includes legions of press photographers until the 35mm SLR took over as their preferred work horse. For years for anyone who wanted to become a freelance photographer, the standard TLR camera was an excellent choice. Compared with the prices of more sophisticated cameras they were not expensive. In fact some of the Japanese models were both cheap and produced fine results. The medium format will allow you to get good quality results in both B/W and colour. Transparencies were big enough to sell to the press etc in the days when size mattered and the cameras themselves are mechanically relatively simple and reliable.
Even now in this digital age I would not be without a 6x6cm TLR for shooting film. I have owned many different models, both German and Japanese, over the years and found them all very good. Such is my fascination for the design principle I have even built 5x4in versions for my own use. You can see a picture of my latest one here. Peter Gowland, the famous American West Coast glamour photographer inspired me, as he has made TLRs as big as 10x8in size.
Finally if when you try and shoot a lively subject, how sure are you that everything is the way you want it at the moment you press the shutter? If you are using TLR you will know.