DOT 5 brake fluids are for when you have that special feeling in you that says "I want to destroy my brake hydraulics."

Your brake hydraulics were made for DOT 3, and if you want to run something better you need to make sure it's compatible. DOT 4 fluids are compatible, but DOT 5 fluids aren't.
Motul RBF 600 is WAY overkill. It'll work, though. It performs at or above the level of a DOT 5, but it's compatible with DOT 3/4 brake systems. Most people feel it's just really expensive for no good reason because there's no way a Maxima will ever come close to needing that performance. Some people just like the idea that they have so much overhead. Up to you.
Valvoline Synpower is widely available and affordable, and it still works for even the hardest autocross usage. That's why people say it's "the best".