FF9 is a rather good game, it took me quite some time to beat because some idiot deleted my save so I didn't beat it after owning it for YEARS. However one day I decided to pick it back up and start over and I'm glad I did, it's an amazing game in the FF series. I also think you'll enjoy the battle system since you liked the older games. The story line is quite good as well and it has a steam punk feel to it as well.. as for the soundtrack well it's great but that's sort of a given due to it's tittle and what not.
The other options,, eh I would honestly say 7 was good but it wasn't as good as the hype says it. Then there is 8 and as much as I loved 8 I'd have to say unless you're a die hard fan of 8 you probably wont like it. Alot of people say 8 is boring and the characters aren't very memorable. The battle system I admit is very flawed with the GF system, the soundtrack is amazing. I personally loved 8 but a lot of people hate 8 as well.
I suggest you stay with your original choice and get 9, I'm sure many people can agree with me when I say it's a fun, interesting, silly and yet depressing game.