In Phantasy Star 3
My personal favorite in the series. The soundtracks are amazing.
Phantasy Star 3's soundtrack seems to be well composed, but unfortunately it is poorly arranged, and as a result you see some balance issues with it. For example, the title screen music has a melody that is trying to come through, but it's hard to hear with all the loud banging chords going on. Similarly, in the Shusoran theme (which is horribly under-used), you can tell that it's a round if you listen to it, but it's very hard to hear the second part.
Another question: In the theme used for high-tech dungeons (as opposed to caves or castle dungeons), what happened to the melody?
One neat thing about PS3's OST is the overworld theme, which adds new instruments with each recruited party member. Furthermore, if the main character is dead, you get to hear a different track. (If you have a late-game save, try giving the main character a Royal Vest and using it as an item during battle to purposefully kill him off.)
As a side note, I am at the start of generation 3 on the generation skip route, and early battles are tough with only one character who is at an appropriate power level. (Mieu and Wren haven't leveled up since the first generation, and Kara starts with level 1 stats, so that leaves Aron as the only character who is as strong as the game is expecting.)
Edit: Found the theme for the dead main character case. Unfortunately, it suffers from a balance problem; the counter-melody is hard to here. https://www.youtube.com/watch?v=PEvcJqBZ284