Lionheart is a really stupid name. It was once a good nickname for, perhaps, some valiant dude. But as a character's name, no. It's like takling a cliched stereotype to the next level.
But Gus/Guy is good. Fits the character, and I like short names like that. I like the name Gus, I don't know why.
Not only is Rydia a badass character, but it is a fantastic name. So is Kain.
Edge is not a fantastic name. It's dull. Oxymoron.
Butz is a terribly created name. Bartz doesn't fix it. Cara is dull. Galuf is great for the character, but, I must admit, it isn't appealing at first. Faris was probably the coolest name in FFV.
Setzer and Locke stand out as cool names from FFVI. Unfortunately, the fact that Locke was a thief totally butchers the uniqueness of the name. Anything blatant becomes ugly. And Shadow sounds like a freaking filler to me. Like they couldn't think of anything real so they looked up synonyms for ninja (Didn't want to name him Ninjo. How about Kino. That'd work. But no. A cave boy gets Kino.). Celes is also unique. I don't know if I like it, but it's unique. But FFVI is filled with bad names. Maybe they tried too hard and came out with crap instead of magic. It happens sometimes.
Cloud wears black armor and carries a gigantic sword. I know that I was mad about the "Locke"thing, but reversing the process is almost dumber. His name should be "Lead" if we're going to name him after non-living nouns. Freaking Cloud... WTF.