I grew up with a Carousel composting toilet in our house. It works well, Draining the urine, using a scoop of sawdust every time, and the occasional insertion of beneficial bacteria, all help prevent odors. We had a 12V fan, as well. Two years is the recommended time for between deposition and cleaning. We used it as our primary family toilet for over 15 years, before my father no longer wanted to clean it. It never broke down, and never had any issues. It can handle a whole family year round.
For individuals or occasional vacation use, I’d recommend the Sun-Mar standard Excel (below).