If your main goal is the least hassle over the long haul, the easiest RV toilet to maintain full-time is usually a simple gravity-flush toilet connected to a standard black tank. It is the most familiar setup, the parts are easy to find almost anywhere, and repairs are usually straightforward. You deal with the black tank, but the system itself is simple: flush, dump, rinse, and repeat. For a lot of full-timers, that beats anything with a more complicated mechanism.
A composting toilet can also be very easy day to day, but only if you are comfortable with separating liquids, managing the solids bin, and emptying it regularly. Some people love them because they reduce black tank use or eliminate it entirely. Others get tired of the extra attention, especially in hot weather or when they move often. The maintenance is not hard, but it is more hands-on than many first-time full-timers expect. If you like a dry system and do not mind learning the routine, it can be a good choice.
Macerating toilets are convenient in some rigs, especially if the toilet location is awkward, but they add another layer of electronics and moving parts. When they work, they are nice. When they clog or fail, you are dealing with a more expensive and annoying repair than a basic gravity toilet. For full-time use, that extra complexity is usually the tradeoff people regret later.
Cassette toilets are simple in a different way, and they can be great in smaller RVs or vans. The waste tank is smaller, so you empty it more often, which can be fine if you stay near dump stations. But for full-time living, frequent dumping becomes the downside. If you are moving around a lot or boondocking, that routine can get old quickly.
What makes a toilet easy to maintain is not just the toilet itself. It is also tank size, how many people are using it, whether you boondock, and how easy it is to rinse and dump the system. A large black tank with a good flush valve and a clear rinse routine is often the sweet spot for long-term living. Use plenty of water, dump before the tank gets too full, and occasionally flush the tank thoroughly so solids do not build up. Keeping the tank sensors from getting gunked up also helps more than people think.
If you want the lowest-stress setup overall, I would lean toward a standard gravity-flush toilet with a black tank in a rig that has decent tank capacity. It is not flashy, but it is dependable, cheap to maintain, and easy to service almost anywhere. If you want less smell and do not mind a different routine, a composting toilet is worth considering. The real answer depends on how often you dump, how much water you have, and how much maintenance you are willing to do yourself.
