Chrono Trigger partisans usually have this track rated higher than I do. Chrono Trigger may have the greatest soundtrack of any video game, bar none; it is the most represented of any game in this Top 50.
I will say this, though--Chrono Trigger excels at atmosphere music, music that sets the tone for whatever action is going on. All the boss battle tracks are superior, and many of the background music tracks are classics. (Though I do not care for the "outside of town" music in A.D. 1000, and will not be persuaded otherwise. It's the chink in the otherwise unscratchable armor.)
But Chrono Trigger is awfully weak on character themes. I don't care for any of them, actually, except Crono's (which doubles as the main theme for the game) and this one. Marle's theme is just terrible, Lucca's is fun but not fitting of her character in any discernible way, Ayla's is more fitting but not very good music. Robo's theme music is good and was among the final cuts for this list.
But Frog's Theme is a great piece of music that hits all the right notes. First and foremost, it's simply good music, and secondly, it's very appropriate music for the character: Heroic, tragic, and a little bit angsty. The consensus of Chrono Trigger fans seems to be that Glenn/Frog is one of the great RPG characters ever. He wouldn't crack my top 10. The "woe is me" angst with him is either poorly played or just spread on too thick, but for a legendary hero it sure took a lot of effort on Team Crono's part to get him to get off his ass and do anything. (I care even less for Locke of Final Fantasy VI, which is appropriate since there's a lot of overlap in those two characters' fan clubs, which is appropriate since they're both whiny angst-balls.)
But I will say this: Frog gets a way better character theme than Locke. Which is saying something, because Locke's theme isn't half bad.
I don't think I'm holding my lukewarm attitude about Frog against him in ranking his theme; it is very good, but then, everything on this list is very good. But it is a point in the composer's favor whenever one's opinion of a character's theme music seems inseparable from one's opinion of the character. That's how you know the music is appropriate.