I spend more time on my FW tanks--pruning plants, cleaning (I do wish there were as many detrivores available for FW setups), water changes, etc. The SW setups--check the water level daily, clean the glass every other week, water changes every other week (weekly for the 10). Feed. Much easier, much less time.
It does require a bigger up front invesment, both in your time spent researching critters, and in money since there are some equipment differences, and of course most of the SW organisms are pricier than the common FW options. But--I love all my tanks, and wouldn't get rid of any of them. If the maintenance is something you'll see as a burden, I don't see how even a FW tank can be an option.