Probably the immersive (in terms of gameplay) FFA in the series I've played so far...

User Rating: 8.5 | Final Fantasy V Advance GBA
Well, this one is refreshing break from the previous title. The dreaded FF4. You've got 5 playable char but ends up with 4 in the end the other replacing the (spoiler alert) dead one.

FF2 has more defined graphics than this one ,it's my opinion anyhow.
The BGMs are great though. Love the "Battle at The Bridge" song.

Its the job system that keeps this game interesting. The job classes is somewhat tied to the whole storyline. You acquire more jobs as you recover the crystal shards.
This system, always something new and different with each FFA series, will keep you busy. Not only you have to level up your characters but also level up their jobs by acquiring APs from defeated monsters. Think of it as EXP for your jobs. When you level up a job you can unlock skills and magic.
Then you add it up with weapon/armor/items/jobs/skills with lots of multiple possible combinations, you've got a game that's so fun and immersive.
One thing I don't like is the "achievement reward". Like take for example, if you defeat a very hard boss you only get a badge and nothing more. WTH.