I couldn't disagree more with the "limited in terms of behavior and lifestyle" comment. The most boring saltwater fish I have ever owned had more personality than any freshwater fish I've ever seen or owned. Just a few examples of some saltwater behaviors and fish that have a ton of personality.
Eels/fish living with and having their mouth and body cleaned by shrimp
Gobies pairing with shrimp and sharing burrows/protecting each other
clownfish hosting anemones/powerheads etc.
Tangs that will follow you around and stare at you through the glass all day long
Triggerfish, which have more personality than any fish I've ever seen
Groupers/lionfish/anglers/rays/sharks/octopus the options and different behaviors are endless.
I can stick my hand in my 28 gallon reef and handfeed any fish in there, get attacked by the clowns defending their anemone, have my hand cleaned by shrimp, and have every hermit crab in the tank race towards my hand to get on it and start picking at my skin. The personality and behavior is just on a completely different level than freshwater.
Also, if you buy healthy saltwater fish, properly acclimate them, and quarantine them, you shouldn't be losing more saltwater fish than freshwater. I'm 3 years in and have yet to lose a single saltwater fish or shrimp.